Wound dressing sealant and use thereof

ABSTRACT

Embodiments disclosed herein are directed to sealing compositions for negative pressure treatment systems and wound dressing systems, devices containing the same, apparatuses, uses and methods for creating a main wound dressing portion for use in wound care, more particularly for sealing a trimmable dressing, having a main dressing portion or cell in fluid (e.g., gas) communication with additional dressing portions or cells, for use in woundcare, more particularly that may be used for the treatment of wounds. In particular, some embodiments are directed to compositions for improving the versatility of wound dressings for wounds of different shapes or sizes.

Embodiments described herein relate to compositions, devicesincorporating the same, apparatuses, kits, their uses in wound care, andmethods for the treatment of wounds and for creating a main wounddressing portion for use in wound dressing, for example in advancedwound management, particularly, but not exclusively, in negativepressure therapy (TNP therapy).

Different types of wound dressing exist for aiding in the healingprocess of a human or animal subject in need thereof. These includedifferent types of materials, for example, gauze and/or foam withoverlying drapes, and composites thereof, provided in assembled layersand in a selection of sizes or shapes, typically square or rectangularshapes. Advanced wound management dressings address specific woundtherapies by means of tailored dressing components, particularly, butnot exclusively, TNP therapy dressings incorporate a means fortransmitting negative pressure to the wound, and a fluid-tight drape forenclosing a negative pressure, provided as independent components or asa composite dressing.

We have found, as a first problem, that certain wounds and bodytopography cannot be adequately dressed using the existing selection ofcomposite TNP dressings, for example vein harvest wounds extending thelength of a subject's leg exceed available dressing dimensions ordiabetic foot ulcers where complex topography prevents rectangulardesigns from conforming adequately to tight body contours.

We have found, as a further problem, that advanced wound therapy and inparticular TNP therapy, cannot therefore be applied to those woundswhich perhaps have the greatest need for this therapy, but ratherconventional wound care must be relied on.

We have therefore defined a need for improved dressings, moreparticularly but not exclusively composite TNP therapy dressings, whichexhibit enhanced adaptability in wound care.

It is an aim of certain embodiments to at least mitigate theabove-mentioned problems. Certain embodiments disclosed herein relate toimproved compositions and their use in combination with dressings toconfer enhanced adaptability in wound care, preferably in TNP woundcare. Dressings applied in combination with such compositions may haveadvantages over traditionally applied dressings which may be moredifficult to apply, particularly around wounds such as lengthy incisionsites or irregularly shaped wounds. Dressings applied to such woundswith use of such compositions may be of comparable effectiveness todressings applied in traditional manner to more regular sized or shapedwounds. Wounds dressed with such dressings in combination with suchcompositions may enable the application of TNP therapy. Also disclosedare improved methods of use and systems for use of the compositions incombination with dressings, preferably in negative pressure woundtherapy.

It is an aim of certain embodiments to provide means to enable compositewound dressings to more universally be used on wounds of differentshapes or sizes.

It is an aim of certain embodiments to provide a dispensable sealantcomposition for a composite wound dressing which can more universally beused on wounds of different shapes or sizes.

It is an aim of certain embodiments to provide a device including suchcomposition for dispensing in improved manner to a composite wounddressing to more universally be used on wounds of different sizes orshapes.

It is an aim of certain embodiments to provide a wound dressing kitincluding a composite dressing, preferably an advanced wound managementdressing, more preferably a composite TNP therapy dressing, togetherwith a sealant composition, adapted to be applied in conjunction at awound site.

It is an aim of certain embodiments to provide an apparatus in the formof a composite wound dressing which can more universally be used onwounds of different shapes or sizes.

It is an aim of certain embodiments to provide a method of treating awound by sealing a composite dressing which can more universally be usedon wounds of different shapes or sizes.

In one embodiment, there is provided a dispensable composition forwoundcare, wherein the composition is dispensed into a wound dressinglocation, said wound dressing comprising:

-   -   a backing layer having an upper surface and a lower surface,        otherwise termed a backing sheet having two faces, and defining        a perimeter configured to be positioned over skin surrounding a        wound site;    -   an optional wound contact layer;    -   one or more transmission layers provided directly or indirectly        to the lower backing layer surface, or otherwise configured to        be positioned below the backing layer, or otherwise positioned        at or on one side of one face of the backing sheet,    -   or enclosed between the backing layer and the wound contact        layer, where present; and    -   a port configured to transmit negative pressure through the        backing layer for the application of topical negative pressure        at the wound site        wherein removing a portion of the wound dressing directly        enclosing the transmission layer to create a main wound dressing        portion with one or more exposed portions wherein the        transmission layer is exposed at a portion thereof,    -   said exposed portion(s) being the location as hereinbefore        defined, the dispensed composition seals the exposed portion(s).

The composition is particularly for creating a main wound dressingportion for use in wound care more particularly for sealing a trimmabledressing, having a main dressing portion or cell in fluid (e.g., gas)communication with additional dressing portions or cells, for use inwoundcare, more particularly for treatment of a wound site,

The composition may be dispensed into or onto the exposed portion orboth. By this means the dispensed composition impregnates or envelopesthe exposed portion or both.

Preferably the dispensed composition impregnates the exposed portion.This has the advantage of enhanced robustness whereby the seal formspart of the dressing.

Alternatively the dispensed composition envelopes the exposed portion.This more resembles a simple repair applied to the upper surface of thedressing. Choice of dispensing by impregnation or enveloping may beselected according to the nature of the dressing to be sealed, inparticular its laminar structure, and more particularly the laminarstructure at the exposed portion thereof. Optionally the compositionimpregnates and additionally envelopes the sealed portion therebyproviding a seal operating at internal surfaces of the transmissionlayer and external surfaces of the dressing. Composition may bedispensed directly at the exposed portion through the exposed facethereof, or indirectly via the backing layer or backing sheet or via theoptional wound contact layer, thereby internally penetrating the exposedportion.

Some embodiments may further comprise a device comprising thecomposition, an apparatus in the form of a dressing for use with thecomposition, kits thereof, uses and methods of therapy. Some embodimentsmay further comprise a source of negative pressure configured to supplynegative pressure through the port. Some embodiments may furthercomprise retention strips or sealing strips configured to hold in placeor seal the dressing to skin surrounding a wound.

In another embodiment, a method of creating a main wound dressingportion for use in dressing or otherwise of treating a wound comprises:

-   -   providing a wound dressing as hereinbefore defined comprising:    -   a backing layer, otherwise termed a backing sheet;    -   an optional wound contact layer; and    -   one or more transmission layers as hereinbefore defined    -   removing a portion of the wound dressing to create a main wound        dressing portion with one or more exposed portions;    -   optionally positioning the main wound dressing portion over a        wound and sealing the main wound dressing to skin surrounding        the wound,    -   and dispensing a composition as hereinbefore defined to a        location comprising the one or more exposed portions of the main        wound dressing portion thereby sealing the exposed portion(s);        and    -   optionally applying negative pressure to the wound through the        backing layer of the main wound dressing portion.

Sealing a wound dressing to skin may be prior to creating a main wounddressing portion and prior to dispensing composition or may besubsequent to creating a main wound dressing portion and prior to orsubsequent to dispensing composition. Accordingly the method may be amethod relating to dressing manufacture for use in dressing wounds ormay be a method relating to dressing wounds. As is used herein thebacking layer represents a gas impermeable membrane. Also referred toherein as wound cover or drape. Some examples of materials suitable forbacking layers included thin polyurethane films, which may optionally becoated with adhesive. It is also possible that a number of laminates bebrought together to form multi-laminar backing layers, in such cases thedescription of the upper and lower surfaces of the backing layer aretaken to mean the upper and lower surfaces of the complete backinglayer.

As is used herein, a dressing also comprises one or more transmissionlayers and other layers (such as absorbent material) positioned beneaththe backing layer. For example, one or more transmission layers or otherlayers may be positioned or enclosed between a backing layer and anoptional wound contact layer, for example, sealed therebetween. Thetransmission layer(s) may be in turn positioned between the backinglayer and (optional wound contact layer and) a wound site over which thedressing is configured to be positioned, for example sealedtherebetween.

A transmission layer as described herein allows transmission of fluidsuch as air, and optionally additionally other gases and liquids, awayfrom a wound site into upper layer(s) of the wound dressing, the port,and therefrom to a fluid canister if present and/or into a negativepressure pump. A transmission layer may assist in maintaining an openair channel to communicate negative pressure over the wound area evenwhen the dressing is handling substantial amounts of exudates. The layershould remain open under the typical pressures that will be appliedduring negative pressure wound therapy. Preferably, a transmission layerremains open over an area corresponding to the wound site, and therebyensures that the whole wound site sees an equalized negative pressure.Alternatively the transmission layer may comprise one or more specificair paths which remain open, such as in and between bridging portions ofa wound dressing as described further below.

A transmission layer may comprise voids or may comprise one or morematerials which transmit fluid, or may be a combination thereof. Thetransmission layer may incorporate other functional materials providedthat it is still capable of transmitting negative pressure, andpreferably also liquid fluids. In some embodiments, the transmissionlayer is capable of transmitting wound exudates and other compositionsof matter.

Some examples of materials suitable for a transmission layer include athree dimensional structure, for example, a knitted or woven spacerfabric (for example Baltex 7970 weft knitted polyester), although othermaterials such as foam (e.g., reticulated foam), nonwoven materials(e.g., an acquisition distribution layer as described below) could ofcourse be used. Alternatively or additionally the transmission layer mayincorporate absorbent material and absorb liquid drawn away from thewound under the applied negative pressure.

Some embodiments described herein include a trimmable dressing, having amain dressing portion or cell in fluid (e.g., gas) communication withadditional dressing portions or cells. As is used herein, a maindressing portion represents a portion which has a size or shape orprofile or articulation which is compatible with a wound or wound siteto be dressed. One or more additional portions or cells may be removedto provide a dressing having a size or shape or profile or articulationwhich is to be compatible with a wound or wound site to be dressed.Preferably a large surface area, or elongate main dressing portion isprovided to dress a similarly large surface area or elongate wound; forexample portions or cells may be retained to provide such a largesurface area, or elongate main dressing portion, or portions or cellsmay be removed to dress a correspondingly reduced surface area orreduced length wound. preferably a shaped main dressing portion isprovided to dress a similarly shaped wound; or a shaped main portion isprovided to dress a wound incorporating or adjacent a protrusion such asa device, for example a pin, or such as a body part such as a digit, forexample one or more additional portions or cells may be conformed toprovide a shaped dressing; preferably a profiled main dressing portionis provided to dress a similarly profiled wound or wound site, such as awound located on complex body topography, for example one or moreadditional portions or cells may be conformed to provide a profileddressing; preferably an articulated main dressing portion is provided todress a similarly articulated wound or wound site such as a woundlocated on a joint, for example one or more additional portions or cellsmay be articulated.

A main dressing portion or portions and additional portions or cells asdescribed herein may be connected by one or more bridge portionsincluding one or more transmission layers as described above, in otherwords a bridging portion underneath the backing layer, or otherwisepositioned at or on one side of one face of the backing sheet, thebridging portion comprising at least one material layer configured totransmit negative pressure from the first portion through the bridgingportion. In some embodiments, the at least one material layer in thebridging portion has a smaller dimension or a different materialstructure than a corresponding dimension or material structure of thefirst portion, for example the one or more transmission layerscomprising one or more bridging portions having a smaller width thanadjacent portions of the one or more transmission layers or than themain dressing portion, or the one or more transmission layers comprisingone or more bridging portions having a smaller height than adjacentportions of the one or more transmission layers or than the maindressing portion.

As is used herein, an exposed portion of transmission layer represents aportion which the backing layer is not configured to enclose and sealagainst a surface such as a wound site, for example the backing layerand optional wound contact layer do not enclose the transmission layer.For example, a section of transmission layer and overlying backing layeris absent, whereby the remaining transmission layer terminates inopen-ended manner, or the backing layer may be partially absent, andadditionally the optional wound contact layer may be partially absent,at which the transmission layer terminates in open-ended manner. It maybe desired to seal such exposed portion of transmission layer (andexposed portions of other layers). As is used herein, sealing representssealing in manner to contain fluid, more preferably in manner to containnegative pressure.

As is used herein, fluid represents liquid and gas. However it is notintended that “fluid” should encompass “vapour”, a favourable moisturevapour transmission rate (MVTR) being a requirement of dressingsenvisaged herein. The backing layer is impermeable or substantiallyimpermeable to fluids including wound exudate. The backing layer isair-tight or substantially air-tight, whereby a negative pressure may bemaintained at a wound site to which the dressing is applied and sealedwith the composition. Wound exudates and other fluids may be containedwithin the wound site and/or dressing and any collection meansassociated therewith.

As is used herein, a dispensable composition represents a compositionhaving viscosity in the range from 5 to 300 Pa·s, preferably 10-100Pa·s. Viscosity (q) is determined in accordance with DIN EN ISO3219:1994, Annex B. For some embodiments viscosity is in the range 20-80Pa·s. The composition parts may be combined and allowed to partiallycure to a suitable viscosity for application, or may have propertiessuch that a suitable viscosity reduction is achieved when subject toshear forces during application. The composition may have flowproperties such that it can be drawn within transmission layer(s) atexposed portion(s) by the prevailing negative pressure and then cure.The composition ay for example flow to a distance of up to 25 mm, eg 1mm to 25 mm. The cured sealant preferably retains a degree of flow orconformability, for example extensibility, such that it can accommodatethe dynamic conditions encountered when on the skin.

As is used herein a TNP system may be operated with any suitable sourceof negative pressure, including and not limited to pumps, springs (SNaP)and any other functional equivalents.

As is used herein, a wound dressing represents a composite wounddressing, preferably an advanced wound management dressing tailored toinclude specific wound therapy provision for i.a. management of woundexudates (eg ALLEVYN Gentle Border, DURAFIBER, ALLEVYN Life), infectionmanagement (eg ACTICOAT, IODOSORB), iv site care (eg IV3000), managementof compromised skin about the wound, TNP (eg RENASYS F/AB, PICO, KCIPrevena, Kalypto Medical Inc NPD1000 NP Wound Therapy System), postoperative care such as surgical drapes (eg OPSITE), temporary bioskindressings (eg BIOBRANE) and the like, most preferably a TNP dressing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an embodiment of a wound treatment system;

FIGS. 2A-D illustrates the use and application of an embodiment of awound treatment system onto a patient;

FIG. 3A illustrates an embodiment of a wound dressing in cross-section;

FIG. 3B illustrates another embodiment of a wound dressing incross-section;

FIG. 3C illustrates another embodiment of a wound dressing incross-section;

FIGS. 4A and 4C illustrate an exploded view of an embodiment of a wounddressing;

FIG. 4s B and 4D illustrate a cross sectional view of an embodiment of awound dressing;

FIGS. A1-A4 and A7 illustrate embodiments of commercially availablewound dressings trimmable for sealing with the present composition, tosize, to profile on complex topography, or to shape around a fixationdevice or for puncture repair;

FIGS. A5-A6 illustrate the use and application and sealing ofembodiments of FIGS. A1-A4 onto a patient;

FIGS. B1-B2 and C1-C7 illustrate the spacer nozzle relationship of anapplicator for dispensing composition to a trimmable dressing;

-   -   and C1-C3 also illustrate the sealing of embodiments of wound        dressings; and C6 also illustrates a novel nozzle head for an        applicator;

FIG. 5A illustrates an embodiment of a wound dressing trimmable at abridge portion;

FIG. 5B illustrates another embodiment of a wound dressing trimmable ata bridge portion;

FIGS. 5C and 5D illustrate the use and application and sealing ofembodiments of FIGS. 5A-5B onto a patient;

FIG. 6 illustrates an embodiment of a trimmable wound dressingcomprising a plurality of portions or cells;

FIG. 6II illustrates the use and application and sealing of anembodiment of FIG. 6 onto a patient;

FIG. 7 illustrates an embodiment of a trimmable T-shaped wound dressingcomprising a plurality of portions with multiple port attachment sites;

FIG. 7II illustrates the use and application and sealing of anembodiment of FIG. 7 onto a patient;

FIG. 8 illustrates an embodiment of a trimmable wound dressing withmultiple port attachment sites; and

FIG. 8II illustrates the use and application and sealing of anembodiment of FIG. 8 onto a patient.

FIGS. 9A and 9B illustrate one embodiment of spacer layer material;

FIGS. 10A-10D illustrate one embodiment of acquisition distributionlayer material;

FIGS. 11A and 11B illustrate one embodiment of absorbent layer material;

FIGS. 12A and 12B illustrate one embodiment of obscuring layer material;

FIG. 13 illustrates one embodiment of an adhesive spread on cover layermaterial;

FIGS. 14A-14B illustrate one embodiment of a trimmable dressing having areduced height bridging portion;

FIG. 15 illustrates an embodiment of a trimmable wound dressingcomprising a plurality of portions or cells;

FIGS. 16A and 16B illustrate another embodiment of acquisitiondistribution layer material; and

FIGS. 17A through 17C illustrate another embodiment of acquisitiondistribution layer material.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments disclosed herein relate to compositions, devices,apparatuses, uses, kits and methods of treating a wound with reducedpressure, including pump and wound dressing components and apparatuses.The apparatuses and components comprising the wound overlay and packingmaterials, if any, are sometimes collectively referred to herein asdressings, unless otherwise indicated or intimated. Throughout thespecification, the terms sealant and composition are hereinafter usedinterchangeably unless otherwise indicated or intimated.

It will be appreciated that throughout this specification reference ismade to a wound. It is to be understood that the term wound is to bebroadly construed and encompasses open and closed wounds in which skinis torn, cut or punctured or where trauma causes a contusion, or anyother superficial or other conditions or imperfections on the skin of apatient or otherwise that benefit from reduced pressure treatment. Awound is thus broadly defined as any damaged region of tissue wherefluid may or may not be produced. Examples of such wounds include, butare not limited to, abdominal wounds or other large or incisionalwounds, either as a result of surgery, trauma, stemiotomies,fasciotomies, or other conditions, dehisced wounds, acute wounds,chronic wounds, subacute and dehisced wounds, traumatic wounds, flapsand skin grafts, lacerations, abrasions, contusions, burns, diabeticulcers, pressure ulcers, stoma, surgical wounds, cosmetic wounds, traumaand venous ulcers or the like. Wounds may include readily accessible anddifficult to access wounds, exposed and concealed wounds, large andsmall wounds, regular and irregular shaped wounds, planar andtopographically irregular, uneven or complex wounds, more preferably ona site selected from the torso, limb and extremities such as heel,sacrum, axial, inguinal, shoulder, neck, leg, foot, digit, knee, axilla,arm and forearm, elbow, hand or for sealing a crevice adjacent oradjoining a wound site, selected from such as sacral cleft, fossa andthe like.

It will be understood that embodiments of the present disclosure aregenerally applicable to use in topical negative pressure (“TNP”) therapysystems. TNP therapy sometimes referred as vacuum assisted closureV.A.C.® or negative pressure wound therapy (NPWT) using sub-atmosphericpressure is applicable to a broad range of wounds such as chronicwounds, incisional wounds, open wounds and abdominal wounds or the like.

Briefly, TNP assists in the closure and healing of many forms of wound,by reducing tissue oedema; encouraging blood flow and granular tissueformation; removing excess exudate and may reduce bacterial load (andthus infection risk). In addition, the therapy allows for lessdisturbance of a wound leading to more rapid healing. TNP therapysystems may also assist in the healing of surgically closed wounds byremoving fluid and by helping to stabilize the tissue in the apposedposition of closure. A further beneficial use of TNP therapy can befound in grafts and flaps where removal of excess fluid is important andclose proximity of the graft to tissue is required in order to ensuretissue viability.

During TNP therapy, a suction source such as a vacuum pump or the likeis utilised to create a negative pressure region. That is to say, aregion where an experienced pressure is below that of the surroundings.The suction source creates a negative pressure via a dressing or drapepositioned over and sealed about or around the periphery of the wound.Wound exudate and other potentially harmful material is enclosed underthe dressing or drape and extracted therefrom.

As is used herein, reduced or negative pressure levels such as −X mmHg,represent pressure levels that are below standard atmospheric pressure,which corresponds to 760 mmHg (or 1 atm, 29.93 in Hg, 101.325 kPa,14.696 psi, etc.). Accordingly, a negative pressure value of −X mmHgreflects absolute pressure that is X mmHg below 760 mmHg or, in otherwords, an absolute pressure of (760-X) mmHg. In addition, negativepressure that is “less” or “smaller” than X mmHg corresponds to pressurethat is closer to atmospheric pressure (e.g., −40 mmHg is less than −60mmHg). Negative pressure that is “more” or “greater” than −X mmHgcorresponds to pressure that is further from atmospheric pressure (e.g.,−80 mmHg is more than −60 mmHg).

The negative pressure range for some embodiments of the presentdisclosure can be approximately −80 mmHg, or between about −20 mmHg and−200 mmHg. Note that these pressures are relative to normal ambientatmospheric pressure. Thus, −200 mmHg would be about 560 mmHg inpractical terms. In some embodiments, the pressure range can be betweenabout −40 mmHg and −150 mmHg. Alternatively a pressure range of up to-75mmHg, up to −80 mmHg or over −80 mmHg can be used. Also in otherembodiments a pressure range of below −75 mmHg can be used.Alternatively, a pressure range of over approximately −100 mmHg, or even150 mmHg, can be supplied by the negative pressure apparatus. In someembodiments of wound closure devices described here, increased woundcontraction can lead to increased tissue expansion in the surroundingwound tissue. This effect may be increased by varying the force appliedto the tissue, for example by varying the negative pressure applied tothe wound over time, possibly in conjunction with increased tensileforces applied to the wound via embodiments of the wound closuredevices. In some embodiments, negative pressure may be varied over timefor example using a sinusoidal wave, square wave, and/or insynchronization with one or more patient physiological indices (e.g.,heartbeat). Canisterless NPWT (omitting a dedicated canister to containwound exudate) has also been considered using negative pressure valuesin the same range as conventional NPWT. More preferably −40 to −200mmHg. More preferably −40 to −140 mmHg.

Embodiments address the problem of providing dressings in a range ofsizes and shapes to accommodate irregularly shaped wounds and bodytopography, for example vein harvest wound dressings accommodatingvariations in height and leg-length of individuals, which is impracticalboth to the manufacturer and to the user. Embodiments enhanceadaptability of existing dressings, and of more recently introducedmultisite dressings such as trilobes and quadrilobes. Embodiments enablea portion of a dressing to be removed to create a main wound dressing ofdesired size or shape or profile or articulation, and sealing exposedportion(s) thereof to contain a negative pressure.

Exposed portion(s) as hereinbefore defined are the result of removing aportion of the wound dressing, which may be by any envisaged means, forexample cutting the wound dressing or tearing along a weakened line.Composite wound dressings may comprise a border for affixing around awound, about a central wound contact portion. The dressing ashereinbefore defined may include a backing layer and wound contact layerof similar footprint or surface area to the transmission layer or otherlayers enclosed therebetween (i.e. a borderless dressing) or of greaterfootprint or surface area than the transmission layer enclosedtherebetween (i.e a bordered dressing). Exposed portion(s) ashereinbefore defined result from removing a portion of the wounddressing as hereinbefore defined directly enclosing the transmissionlayer, for example by cutting into or through the backing layer andwound contact layer and the transmission layer therebetween.

The portion(s) of the wound dressing may be removed to size the mainwound dressing portion for positioning over a wound as hereinbeforedefined, for example an incisional wound, an elongate leg wound, anarcuate incisional wound and the like. Similarly the portion(s) of thewound dressing may be removed to shape the main wound dressing portionfor positioning over a wound as hereinbefore defined, such as a flapwound, over a protruding device such as a fixation device or aprotruding body part, to profile the main wound dressing for positioningover a wound as hereinbefore defined, for example on complex bodytopography, or to articulate the main wound dressing for positioningover a wound as hereinbefore defined for example on a flexing joint.

Preferably a dressing is skin compatible. Skin compatible as used hereinrefers to the ability to apply or reapply a dressing and in particular abacking layer or wound contact layer to skin and remove from skinwithout trauma to the wearer, and without causing substantial damage tothe skin. Skin compatible materials include adhesive or non-adhesivematerials such as pressure sensitive adhesive (PSA), typically acrylic,hydrocolloid, silicone and silicone based materials and other materialsas hereinbelow recited. A particularly well known skin compatiblematerial comprises silicone or is silicone based, and skin compatiblematerials are envisaged having properties corresponding to silicone orsilicone based material.

Composition and Method for Dispensing

The composition may be selected from a curing system and a non-curingsystem. Ideally this is a material that will not flow substantially fromits application site but that during application is either shearthinning or shape conformable when subject to load. A curing system maybe selected from a curable one or more parts composition, for examplesilicone curing systems which may include one, two or more part siliconesystems and may include a range of curing mechanisms, epoxy curingsystems, cyanoacrylate curing systems, polyurethane curing systems,polymeric systems functionalised with silicone chain linking functionalgroups, polymeric system functionalised with polyurethane curingfunctional groups, drying system such as an elastomer rendered fluid bythe presence of a volatile solvent, spray on elastomers such as acrylicin water or solvent base, UV or light curing systems.

A non-curing system may be selected from a one or more part composition,for example a putty, a jelly such as petroleum jelly, grease such assilicone grease, a gel such as a hydrogel, organogel or xerogel, apaste, a colloidal system such as a hydrocolloid.

Preferably the composition dispensed to a location as hereinbeforedefined forms an elastomeric seal.

Curing time of a curable composition is not a limiting feature. A curingcomposition usefully has curing time at 23° C. in the range from 0.05min to 24 hours, eg 0.5 to 20 min, more preferably from 0.5 to 18 min,more preferably from 0.5 to 16 min, most preferably 12 min, mostpreferably 0.5 to 5 min. Cure time is manual kinetic as known in theart.

A number of methods are known in the art to monitor the cure of liquidpolymers and in particular RTV-2 silicones, these vary from continuousmonitoring across the full cure profile of the material with instrumentssuch as scanning vibrating needle curemeters (B. G. Willoughby and K. W.Scott, Understanding cure with the scanning vibrating needle curemeter(scanning VNC), RTL/2844, Rapra Technology Limited, Shawbury) ordifferential scanning calorimeters (L. M. Lopez, A. B. Cosgrove, J. P.Hernandez-Ortiz, T. A. Osswald, Modeling the Vulcanization Reaction ofSilicone Rubber, Polym. Eng. Sci., 2007, 47, 675-683) through toempirical single point determinations typically based on clear physicalchanges, for example recording the time taken to reach the gel point.

During the trials described in the examples it was found that transferof uncured sealant from the application site to other surfaces was aclear disadvantage. For the purpose of defining an unambiguous singlepoint on the cure profile, cure time is taken to mean manual kineticcure time. Manual kinetic cure time is herein defined as the cure time(at a specified temperature) at which material is no longer transferredto skin (i.e. a fingertip) when subject to a light, brief touch.

Due to the temperature dependence of the cure profile on addition cureRTV silicones it is important that comparison between any measurementsis carried out at the same temperature and that the temperature bereported. Guidance set out in Methods of Test for Surgical Dressings inthe British Pharmacopoeia (BP), 1993, 14^(th) edition, A222, Appendix XXis that the temperature of a regulated atmosphere is taken as 20° C.±2°C. Within the silicone industry there are many instances where curingparameters of addition cure RTV-2 silicones are reported at a nominaltemperature of 23° C., this falls in line with standard test methods forother temperature dependant properties such as viscosity (when measuringviscosity DIN EN ISO 3219:1994 describes a preferred measurementtemperature of 23.0° C.±0.2° C.), examples of this include: Pot Lifereported by Wacker Silicones (at 23° C. on Technical data sheet forSilpuran® 2445 A/B, Version 1.3 & Technical data sheet for Silpuran®2450 A/B, Version 1.3, Wacker Chemie A G, München); Maximum Working Timereported by Bluestar Silicones (at 23° C. on The Silbione® Difference,Silicones for Healthcare Applications, Bluestar Silicones France SAS,Lyon) and Pot Life reported by Momentive (defined as the time forinitial viscosity to double at 23° C. on Silicone Gels for HealthcareApplications, 152-053-00E-GL, Momentive Performance Materials Inc.,Columbus). When considering the temperature of a material applied toskin, it should be noted that the temperature of skin is nominally takenas 32° C. In a clinical environment, when a curing RTV-2 silicone isapplied as a thin bead, layer or film in intimate contact with the skin,it has been assumed that the material will reach thermal equilibriumwith the skin rapidly.

Within the literature other discrete points along the cure profile areroutinely used, of note are: pot life, this usually indicates themaximum period of time after which the mixed silicones may still beworked, poured, spread etc. Where flow is an important requirement potlife is usually quoted as the time required for the initial viscosity todouble (Elastosil, Processing RTV-2 silicone rubbers, 6020e/06.06,Wacker Chemie AG, München) and tack free time, this is an appropriatemeasure when considering a rubber (by definition the material must nothave any discernible tack or grab once cured) and may be assessed in asimilar way to manual kinetic.

Preferably the composition has cure time as hereinbefore defined at 23°C. in the range from 0.5 min to 20 min, more preferably from 0.5 to 18min, more preferably from 0.5 to 16 min, most preferably 12 min, mostpreferably 0.5 to 5 min. Cure time is manual kinetic as hereinbeforedefined.

Values at 32° C. are particularly instructive in the presentapplication, preferably cure time at 32° C. is in the range 0.5 to 10minutes, more preferably 0.5 to 8 minutes, most preferably in the range0.5 to 7 minutes.

Tack

Tack is hereinbelow measured as maximum force required to separate aprobe from cured composition. However for the purpose of determiningtack-free or low tack time, a touch and lift test was performed atintervals with the finger, on controlled samples, and tack free or lowtack time determined as the time at which the sample did not adhere toand lift with touch.

Preferably tack-free time is in the range from 0.5 to 25 minutes, morepreferably from 0.5 to 22 minutes. Preferably the composition has tackas hereinbeforedefined at a period in the range from 0.5 minutes to 22minutes after combining such as to not adhere items such as paper orclothing which contact the composition. Finger tack is a relativelysubjective evaluation which can be obtained by touching the surface ofthe dispensed composition to determine the “stickyness” thereof.Descriptive terms such as high H), low (L) and moderate (M) can then beattributed as a preliminary measure.

Preferably a composition intended for external seal of the exposedportion forms a substantially tack free seal in a period as hereinbeforedefined. Preferably a composition intended for internal seal within thebridging portion forms a substantially tack free to moderate tack seal.

Viscosity

Preferably as hereinbefore defined, compositions having low viscosity inthe range 11-14 Pa.^(s-1) are of particular advantage when dispensedinternally.

A composition may be shear thinning, to assist application, for exampleexhibiting change in viscosities with shear rate, for example asfollows:

Target shear rate (s⁻¹) viscosity (eg range) mPa · s⁻¹ 1.0  250(240-270) 2.50 80 (65-94) 5.00 55 (42-63) 10.00 40 (33-51) 25.00 20(20-25) 50.00 15 (9-21)  100.00 10 (5-13) 

Shear thinning compositions advantageously revert to their restviscosity and remain in place once the dispensing force or applicatorforce is removed.

Alternatively a rapid onset of cure stabilises the composition inposition. Preferably composition penetrates within the transmissionlayer and optional additional layers to a distance of from 1 mm to 10mm, for example substantially 5 mm. Penetration should not exceed 25 mm.

Extensibility

A dressing as hereinbefore defined should approximate as closely aspossible to skin, to minimize discomfort and to maximize the beneficialeffects thereof. WO2009/156709 discloses the properties of skinspecifically in relation to extensibility, which are to be approximateby a dressing. Preferably the composition cures to a seal whichapproximates to the extensibility of the dressing which it seals and/orthe extensibility of the skin of the wearer. Preferably the compositionafter curing as a sample with a height of 1 mm has extensibilitycomparable to or greater than the main dressing portion, bridgingportion, trimming portion(s) or component layers thereof up to a maximumcorresponding to the backing sheet. For example for the backing sheetthe load required to produce a 20% extension at a rate of extension of300 mm per minute is in the range of less than or equal to 1.4 kgf percm width (kgfcm⁻¹), preferably in the range 0.001 to 1.4 kgf cm⁻¹expressed preferably as 0.001 to 14.0 kgf cm⁻² to produce 20% extension,more preferably in the range 0.001 to 5.0 kgf cm⁻².

The extensibility of a typical spacer layer is approximately: 0.08kgfcm⁻¹ (Direction A); 0.07 kgfcm⁻¹ (Direction B)

The extensibility of a typical superabsorber layer (Laminate EU33 topfilm, superabsorbent airlaid (Chemposite 11C/450 airlaid superabsorbentpad, spacer layer Baltex 7970 and perforated Si wound contact layer isapproximately 0.59 kgfcm⁻¹ (Direction A); 0.78 kgfcm⁻¹ (Direction A).

Preferably extensibility of seal as hereinbefore defined is 0.04 to3.00, more preferably 1.00 to 2.50.

Permanent Set

Permanent set for the cured seal enclosed within the layers may besubstantially 0. In the case of a seal enclosed within the layers thenpermanent set is preferably in the range comparable to Allevyndressings.

Tensile Strength

In the case of a seal enclosed within the layers the compositionbenefits from the support of the dressing and tensile strength valuesmay be widely variable. In the case of a seal enclosed within the layersthen tensile strength is preferably in the range comparable to Allevyndressings.

Elongation at Break

In the case of a seal enclosed within the layers the compositionbenefits from the support of the dressing and elongation at break valuesmay be widely variable. In the case of a seal enclosed within the layersthen elongation at break is preferably in the range comparable to thespacer materials typically present in dressings. Spacer elongation atbreak is 115%. Preferably elongation at break is in the range 5-15%.

Compressibility

Preferably the composition forms a seal having equal or greatercompressibility than the bridging layer. Further detail is given hereinin relation to preferred compressibility of the bridging layer andbridging layer materials when subject to negative pressure. Preferably aseal does not protrude above the exposed portion which is seals,preferably a protruding seal is compressible. Compressibility ismeasured according to penetrometry ASTM 82137, more preferably is in therange 20-500/10 mm.

It will be clear that viscosity for each of Parts A and B is for theas-provided components, prior to mixing. Suitably the components mix toa dispensible viscosity.

Preferably the cured composition has elongation at break as hereinbelowdefined, greater than or equal to 50%.

Preferably the cured composition has tensile strength, as hereinbelowdefined, greater than or equal to 5 kgfcm⁻² Preferably for the curedcomposition permanent set is in the range 20% to 0%.

Preferably the composition is a Silpuran composition as hereinbelowrecited, more preferably is Silpuran 2400™, or a functional analoguethereof, optionally incorporating viscosity and/or cure time modifierproviding increased viscosity and reduced cure time. Preferably thecomposition has translucent appearance after curing. Preferably thecomposition is dispensed within the transmission layer by the firstembodiment method disclosed herein (FIG. C1).

In a first embodiment the composition is dispensing into a location ashereinbefore defined, the location being substantially internal to orreceived within the transmission layer at the exposed portion ashereinbefore defined. In this embodiment, composition is required to bedispensed from an outlet of a dispensing device such as a static mixer,said outlet being capable of being received within the transmissionlayer at the exposed portion as hereinbefore defined. Suitably adispenser comprises a syringe or static mixer comprising a nozzle havingan outlet. Preferably the nozzle is capable of being received within thetransmission layer at the exposed portion in manner that the location atwhich composition is to be dispensed is a short distance within theexposed portion, for example is up to 25 mm distant from the exposedportion, more preferably from 2 mm to 20 mm, more preferably from 3 mmto 18 mm, for example in the range from 5 mm to 12 mm. Composition maybe dispensed via the exposed portion face or via the backing layer orsheet, for example by injection through the backing layer or sheet.Dispensing may be before or after trimming a dressing. Dispensing bythis means may be by puncturing the film either singly or in multipleplaces as described above. Preferably the film is punctured with use ofone or more resiliently deformable needles, for example a plastic needleor with use of one or more limited penetration depth needles. Suchneedle minimizes risk of skin puncture. Alternatively the injectioncould take place prior to dressing placement and removal of the dressinghandle, thus confining the sealant to between the backing layer or sheetand the handle. Dispensing may be prior to trimming the dressingalongside or through the cured sealant to leave a sealed edge.Composition may alternatively be dispensed to intact skin and exposedportion of the dressing located thereover. Composition so dispensedflows into or is drawn into the dressing to the transmission layerthereby sealing.

Composition so dispensed is dispensed to a location deeper into theexposed portion distanced from its face. Composition is dispensed as aband returning back to the face of the exposed portion as the dispensingdevice is withdrawn. A seal so generated is more secure, with morecomprehensive blocking of passageways within the exposed portion of thetransmission layer. Such a seal has a lesser likelihood of presentingleaks when negative pressure is applied. A suitable nozzle for adispensing device includes low aperture nozzles, needles and the like.Nozzles may be formed from plastic. Such nozzles are disposable andpresent no hazard, being non-perforating to human skin. Such nozzles arecurrently available for use with pipette tips.

Composition may be dispensed via multiple point injection at intervalsalong the exposed face, for example through the spaces between thespacer layer struts. Composition may flow to some extent on initialapplication, either or both laterally to the direction of dispensing andadvancing and receding, flow becoming less as composition hardens orcures. This may aid in providing a continuous lateral seal, wherebydispensing intervals along the face of exposed portion may be increased.Nozzle insertion distance within the exposed portion may be selected toconfine the seal spaced a short distance in from the face of the exposedportion, or to allow some spill of composition out of the exposedportion and onto surrounding surfaces such as a preparation plate orskin. Advantages of this embodiment include minimizing the amount ofcomposition required to be dispensed. This in turn allows use of a lowercapacity dispensing device, for example a 5 ml or 10 ml or 15 ml or 25ml syringe or static mixer. The back pressure encountered on dispensingfrom a static mixer increases with the mixer volume, which in turn leadsto a decrease in the viscosity which the static mixer is able todispense. It is generally advantageous to this embodiment to delivercomposition at as high a viscosity as possible to ensure thatcomposition is confined within the exposed portion. A further element inthe total back pressure or resistance encountered on dispensingcomposition is the nozzle aperture of static mixer. For this embodiment,it is desired to dispense composition from a small aperture nozzle, andthis adds to the back pressure. The advantage that this embodimentdelivers of enabling a relatively small volume syringe or mixer to beemployed, allows greater freedom to operate a small aperture nozzle.

Finally we have found that a seal generated by dispensing compositioninternally to the exposed portion according to this embodiment, ishighly effective. The dressing should be trimmed, as hereinbeforedescribed, such that the exposed portion overlies intact skin about awound, and does not overly the wound itself. In the case of a dressinghaving an adhesive or tacky wound contact layer, such as a siliconecontact layer as hereinbefore described, the wound contact layer adheresto the skin about the wound and seals the dressing to skin about theexposed portion and the dispensed seal. Preferably the exposed portionis bordered by a border region at the 2 extremities thereof, for examplea border of backing sheet or layer as hereinbefore defined, preferablyhaving depth in the range 5 mm to 25 mm, more preferably 7 mm to 25 mm,for example 14 mm to 25 mm. The wound contact layer is perforated orotherwise porous to allow transmission of fluids to and from the woundbed, and this may permit flow of composition onto skin directly proximalto the internal seal. This may beneficially enhance the seal between thewound contact layer and skin. In the event that flow of composition toskin directly proximal to the internal seal is not desired, compositionsuitably has a sufficiently high viscosity to restrict flow,alternatively the wound contact layer may be non-porous or non-permeablein the region proximal to an envisaged exposed portion, for example at abridging portion or trimmable portion as hereinbefore defined.Composition may be dispensed to a location as hereinbefore defined in adressing having no obscuring layer, or having window(s) in obscuringlayer at bridging portions or trimmable portion(s). This allows visualcontrol of nozzle insertion distance within the exposed portion ofcomposition, of volume dispensed, and/or of lateral flow enabling asuitable dispensing interval across the face of exposed portion to bedetermined. In the case that no obscuring layer is present it ispreferred that the composition incorporates ADL as hereinbefore definedas transmission layer, rather than spacer layer which may pose a risk ofpenetrating the backing sheet.

In this embodiment preferably the dressing does rot comprise absorbentlayer such as ADL in the bridging portion or at the trimmable portion.

In a further embodiment of the composition for dispensing into alocation as hereinbefore defined, the location comprises the backinglayer or backing sheet adjacent the exposed portion, whereby compositionflows across and covers the exposed portion. In some cases compositionflows a short distance into or is drawn a short distance within theexposed portion. It may be desired to dispense or smooth composition atthe perimeters or extremities of the exposed portion for exampleadjoining a border region, and for example directed slightly back alongthe perimeter or extremity. This has the advantage of advancingcomposition a short distance at the perimeter of the exposed portion,ensuring a total seal and also securing the seal in place. Ascomposition hardens or cures, the viscosity typically increases and flowceases whereby composition is retained at or in the dispensing locationand forms an effective seal.

This further embodiment places performance requirements on thecomposition and the resulting seal, additional to those of the firstembodiment of sealing and mode of dispensing. Specifically compositionrequires a continuous film to be dispensed and formed across the surfaceof the backing layer or sheet bridging onto the exposed portion of anyadditional layers and the exposed portion of the transmission layer andbridging onto the skin surface. Therefore composition must besufficiently viscous and/or cohesive to form an intact film. Such filmmay be thin or may be of appreciable depth and/or thickness of forexample from the order of depth and/or thickness of the backing sheet tothe order of depth and/or thickness of the dressing or of the componentlayers at the exposed portion thereof, for example 1 mm to 5 mm. Shouldsuch film rupture or fail prior to setting or curing of composition thenthe seal will fail. After setting or curing of an intact film, theexposed nature of the seal and its presentation as a film placeadditional requirements of robustness, both to external influences andalso, to its ability to retain integrity across interfaces betweenadjacent layers. These requirements are likely to be greater in the caseof a thin film. Preferably therefore a seal according to this furtherembodiment is characterized by properties of tensile strength, permanentset, and elongation at break, optionally also extensibility, in rangesas hereinbefore defined. In contrast a seal generated according to thefirst embodiment, as hereinabove, is supported in large part by thefabric of the dressing enclosing the seal, whereby requirements oftensile strength, permanent set, elongation at break, are significantlylower, also being enclosed within the lower extensibility dressing, therequirement for extensibility is significantly lower than for thefurther embodiment as herein.

A seal according to this embodiment may be effective from the backinglayer surface across the exposed portion.

As will be apparent, a seal across the exposed portion alone issusceptible to failure at the interface of the backing sheet and exposedportion and any intervening layers.

This further embodiment is likely to be more effective when adopted inrelation to a dressing comprising no additional layers as hereinbeforedefined, thereby better resisting strains introduced by separation atthe interface of additional layer(s) and transmission layer. Additionallayer(s) if present may beneficially be secured at their interfaces witheach other and with transmission layer, by needling, stitching and othermeans as known in the art.

The further embodiment moreover requires that a seal have low profileand/or have compressibility greater than or equal to the surroundingdressing. This is of advantage in minimizing discomfort to the wearerimposed by a protruding ridge at the exposed portion of the dressing.

In one embodiment the composition may comprise any polymers that followa hydrosilylation reaction. One polymer (i) preferably contains alkenylgroups, the other (ii) preferably contains Si—H moieties. The group ofsiloxane polymers is based on a structure comprising alternate siliconand oxygen atoms with various organic moieties attached to the silicon.Curing can be defined as a treatment that decreases the flow of anelastomer. This change is generally brought about by linking reactionsbetween polymer molecules. Where the silicon hydride (Si—H) moiety ispart of a polysiloxane, it is possible for the alkenyl group to eitherbe part of a siloxane polymer or otherwise part of a non-siloxanepolymer. The position of the alkenyl functional group is not criticaland it may be either at the molecular chain terminals or in non-terminalpositions along the molecular chain.

A curing system is preferably apportioned between at least one Part Aand at least one Part B and comprises: one or more alkenyl-groupcontaining polymers (i) having at least one alkenyl group or moiety permolecule, one or more SiH-containing polymers (ii) having at least oneSi—H unit per molecule; and a catalyst (iii) for curing by addition ofalkenyl-containing polymer (i) to SiH-containing polymer (ii).

A “unit” as herein referred represents a group or moiety or partthereof. A “moiety” as herein referred is a group of atoms havingfurther atoms disposed on two or more sides thereabout, ie having two ormore valencies unspecified.

A “group” as herein referred represents a group of atoms having furtheratoms disposed on one side thereof, ie having one valency unspecified.Si—H units herein have the same meaning as SiH units

Polymers (i) and (ii) as hereinbefore defined are fluid-phase polymersincorporating reactive groups which cross-link in presence of catalystto form a copolymer more preferably a cured elastomer. Suitably Part Acomprises catalyst together with polymer (i), and Part B comprisespolymer (ii) optionally together with any remaining polymer (i).Suitably polymers, catalyst and optional further components areapportioned in manner to balance volumes and viscosities of both Parts.Preferably polymer (i) is an alkenylsiloxane-containing polymer.

Preferably the Parts are combined and intimately admixed prior to orduring to dispensing.

Suitably the components and Parts mix to a dispensible viscosity.

Polymers (i) and/or (ii) are commercially available or may be obtainedby known techniques. Suitably polymers (i) and/or (ii) are independentlyselected from known and novel fluid phase homopolymeric, and copolymericpolymers, and their entangled systems and mixtures thereof. Thecompositions, in turn, cure to form copolymers, and may also includetheir entangled systems and mixtures with other non-reactive polymers ifpresent in the composition.

Copolymeric polymers include all hybrids derived from two or moremonomeric species, including alternating, periodic, statistical, random,block, linear, branched, star, graft and pendant copolymers. Entangledsystems include interpenetrating networks (IPNs) andsemi-interpenetrating networks (SIPNs). It is also the case that thesepolymers can incorporate both organic and inorganic moieties.

Preferably polymers (i) and (ii) are selected from silicones, includingsiloxanes and modified siloxanes, polyurethanes (PU) including polyesterand polyether urethanes, elastomeric polyether polyesters, polyglycolicacid, polyacetates such as ethyl vinyl acetate, polyacrylate, polyacidderivatives of polysaccharides, such as carboxyalkylcellulose,carboxyalkylchitosan and copolymers thereof, and their hybrids includingcopolymers, entangled systems and mixtures thereof.

The composition may make use of an addition cure reaction betweenorganohydrogensiloxane units and organoalkenylsiloxane units. Theseunits may be incorporated into a wide range of polymeric, copolymeric,entangled and mixed polymers as hereinbefore defined. Preferred siloxanepolymers (i) and (ii) therefore include these respective units and aremore preferably polyorganosiloxanes. Polymer (i) is preferably apolydiorganosiloxane polymer comprising alkenyl-containing units, morepreferably is a polydiorganoalkenylsiloxane polymer. Preferably polymer(ii) is a polydiorganosiloxane polymer comprising SiH units, morepreferably is a polydiorganohydrogensiloxane polymer.

Examples of hybrid organic-inorganic polymeric systems that have usedboth siloxane and organic units include: acrylate functionalizedsiloxane copolymers, which have found use in contact lenses (U.S. Pat.No. 3,808,178); hybrid grafts where organic polymers are grafted onto apolysiloxane chain or where siloxanes are grafted onto organic polymers,for example in silane graft technology for cross linkable HDPE (U.S.Pat. No. 3,646,155) where hybrid grafts have been used to allow thecross linking of organic polymers through siloxane bond formation;hybrid block copolymers for example silicone-polycarbonate blockcopolymers (U.S. Pat. No. 3,274,155); and copolymers of hybrids ofsilicone and ethylene copolymers, cross-linked with vinyl-containingsilicone copolymers which have found use in coating textiles (US2005/0100692);

IPNs represent a special class of hybrid polymeric systems, thesesystems use a combination of mechanical entanglement and crosslinking inwhich one polymer is cured about another; these include thermoplasticsentangled with platinum catalyzed addition cure silicones such assilicone-urethane IPNs and semi-IPNs including silicone-urethane andsilicone-polyamide systems which are of general application or havefound specific use in coating textiles (U.S. Pat. No. 4,714,739, U.S.Pat. No. 7,543,843); hydrophilic components immobilised in a siliconepolymer (U.S. Pat. No. 5,397,848) which have found use as contact lensmaterial; and silicone polymer cured about a non-reactive polymer ofcomparable adhesion, which have found use in coating textiles (U.S. Pat.No. 7,132,170).

Polymers may also be selected from modified silicones (MS) which finduse as adhesives in catheter tubing and the like.

Preferred compositions comprise a polydiorganosiloxane polymer (i)and/or (ii) and/or their respective combinations with the aforementionedpolymers. A composition in which polymers comprise or consistessentially of polydiorganosiloxane polymers (i) and (ii) has particularadvantages, for example in applications where low toxicity is anadvantage, preferably in medical or dental applications or innon-medical or non-dental applications requiring low toxicity orfavorable biocompatibility.

Alternatively or additionally polymers (i) and (ii) are as commerciallyavailable (Cavi-Care™ A/B, and the like) or variants thereof, optimisedfor viscosity and curing to give a fluid-tight exposed surface(hereinafter skin-formation or “skinning”) as hereinbefore defined.

Polymer (i) and (ii) may comprise respective alkenyl-containing unitsand organohydrogensiloxane units situated along the length of polymerchains, and/or as polymer chain end-capping units or a combinationthereof. Polymer (i) in-chain and end-capping alkenyl units preferablycomprise alkenyl group or moiety R^(Alk) selected from C₂₋₂₀ alkenyloptionally substituted or including one or more aryl groups or moieties.R^(Alk) may comprise terminal or non terminal unsaturation, and may beof the formula i-I:

—R^(Alk1)—CR^(Alk1)═CR^(Alk2) ₂  (i-I)

in which the groups R^(Ak1) and R^(Alk2) are independently selected fromH, C₁₋₂₀ alkyl and C₅₋₂₀ aryl groups and combinations thereof and amoiety R^(Alk1) is selected from a single bond, C₁₋₂₀ alkyl and C₅₋₂₀aryl groups and combinations thereof. One of R^(Alk2) may be a moietylinking to polymer chain. More preferably each R^(Alk) is independentlyselected from vinyl, allyl, propenyl, and from terminally andnon-terminally unsaturated butenyl, pentenyl, hexenyl, heptenyl,octenyl, nonenyl and decenyl groups, most preferably selected from vinyland hexenyl groups.

Preferably polymer (i) comprises a polydiorganosiloxane polymer orcopolymer comprising alkenyl-containing units of the formula (i-II):

═Si—R^(Alk),  (i-II)

more particularly of the formula (i-Ill) and/or (i-IV):

—O—Si R¹R^(Alk)—O—  (i-III)

—O—Si R¹ ₂R^(Alk)  (i-IV)

wherein R^(Alk) is as hereinbefore defined and one or more groups R¹ areorgano groups suitably independently selected from alkyl and arylgroups, more preferably C₁₋₂₀ alkyl and C₅₋₂₀ aryl groups andcombinations thereof, for example from methyl, ethyl, propyl, butyl,pentyl, hexyl, heptyl, octyl, nonyl and/or decyl groups and moieties.

More particularly polymer (i) is selected from the formula i-V and i-VI:

P^(i)—O—Si R¹R^(Alk)—O—P^(i)  i-V:

P—O—Si R¹ ₂R^(Alk)  i-VI

wherein P^(i) denotes the remainder of the polymer chain which mayincorporate same or different units, and R¹ is as hereinbefore defined.

Polymer (i) may also comprise a polyorganosiloxane exhibiting, permolecule, at least two C₂-C₆ alkenyl groups bonded to the silicon andhaving, for example, a viscosity of between 10 and 300 000 mPa·s, thatis to say 0.01 to 300 Pa·s, such that when combined in Part A withfurther Part A components and optionally additionally in Part B withfurther Part B components, Part A, and Part B as appropriate, is (are)of viscosity in a range as hereinbefore defined, which can in particularbe formed of at least two siloxyl units of formula:

$\begin{matrix}{Y_{d}R_{e}{SiO}_{\frac{({4 - d - e})}{2}}} & ({III})\end{matrix}$

in which:

-   -   Y is a C₂-C₆ alkenyl such as vinyl, allyl or hexenyl groups,        preferably vinyl,    -   R is a monovalent hydrocarbon group with no unfavorable effect        on the activity of the catalyst which is generally chosen from        alkyl groups having from 1 to 8 carbon atoms inclusive, such as        the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups,        cycloalkyl groups, such as the cyclohexyl, cycloheptyl and        cyclooctyl groups, and aryl groups, such as xylyl, tolyl and        phenyl,    -   d is 1 or 2, e is 0, 1 or 2 and d+e=1, 2 or 3,    -   optionally all the other units being units of average formula:

$\begin{matrix}{R_{f}{SiO}_{\frac{4 - f}{2}}} & ({IV})\end{matrix}$

-   -   in which R has the same meaning as above and f=0, 1, 2 or 3.

Examples of polymer (i) are, for example, dimethylpolysiloxanescomprising dimethylvinylsilyl ends, (methylvinyl)(dimethyl)polysiloxanecopolymers comprising trimethylsilyl ends or(methylvinyl)(dimethyl)polysiloxane copolymers comprisingdimethylvinylsilyl ends.

A convention accepted in the art for denoting the units of siliconesaccording to the number of oxygen atoms bonded to the silicon is usedhere. This convention uses the letters M, D, T and Q (abbreviations for“mono”, “di”, “tri” and “quatro”) to denote this number of oxygen atoms.This nomenclature of silicones is described, for example, in the work byWalter Noll, “Chemistry and Technology of Silicones”, Academic Press,1968, 2nd edition, on pages 1 to 9.

Polymer (i) may also be a silicone resin bearing at least two alkenyl,preferably vinyl groups. Such silicone resin comprising at least twodifferent siloxane units chosen from those of M siloxane unit of formulaR₃SiO_(1/2), D siloxane unit of formula R₂SiO_(2/2), T siloxane unit offormula RSiO_(3/2) and Q siloxane unit of formula SIO_(4/2),

wherein R denotes a monovalent hydrocarbon group, with the conditionsthat at least one of these siloxane units being a T or Q siloxane unitand that at least two of the M, D and T siloxane units comprises analkenyl group.

The silicone resin could be selected from the group consisting of:

-   -   an organopolysiloxane resin of formula MT^(Vi)Q consisting        essentially of:    -   (a) trivalent siloxane units T^(Vi) of the formula R′SiO_(3/2);    -   (b) monovalent siloxane units M of the formula R₃SiO_(1/2), and    -   (c) tetravalent siloxane units Q of the formula SiO_(4/2)    -   an organopolysiloxane resin of formula MD^(Vi)Q consisting        essentially of:    -   (a) divalent siloxane units D^(Vi) of the formula RR′SiO_(2/2);    -   (b) monovalent siloxane units M of the formula R₃SIO_(1/2), and    -   (c) tetravalent siloxane units Q of the formula SiO_(4/2)    -   an organopolysiloxane resin of formula MDD^(Vi)Q consisting        essentially of:    -   (a) divalent siloxane units D^(Vi) of the formula RR′SiO_(2/2);    -   (b) divalent siloxane units D of the formula R₂SiO₂/2    -   (b) monovalent siloxane units M of the formula R₃SiO_(1/2), and    -   (c) tetravalent siloxane units Q of the formula SiO_(4/2)    -   an organopolysiloxane resin of formula M^(Vi)Q consisting        essentially of:    -   (a) monovalent siloxane units M^(Vi) of the formula        R′R₂SiO_(1/2); and    -   (b) tetravalent siloxane units Q of the formula SiO_(4/2), and    -   an organopolysiloxane resin of formula M^(Vi)T^(Vi)Q consisting        essentially of:    -   (a) monovalent siloxane units M^(Vi) of the formula        R′R₂SiO_(1/2);    -   (b) trivalent siloxane units T^(Vi) of the formula R′SiO_(3/2),        and    -   (c) tetravalent siloxane units Q of the formula SiO_(4/2)    -   wherein R denotes a monovalent hydrocarbon group such as methyl        and R′ denotes a vinyl group:

Such resins are well-known branched organopolysiloxane oligomers orpolymers which are commercially available. They are provided in the formof solutions, preferably siloxane solutions.

Polymer (ii) in-chain and end-capping polyorganohydrogensiloxane unitsare preferably selected from the formula ii-I and ii-II:

—O—Si R²H—O—  ii-I

—O—Si R² ₂H,  ii-II

more preferably polymer (ii) is selected from formula ii-III and ii-IV:

P^(ii)—O—Si R²H—O—P^(ii)  ii-III

P^(ii)—O—Si R² ₂H  ii-IV

whereinP^(ii) denotes the remainder of the polymer chain which may incorporatesame or different units and one or more groups R² are organo groupssuitably independently selected from C₁₋₂₀ alkyl, C₅₋₂₀ aryl andcombinations thereof, for example from methyl, ethyl, propyl, butyl,pentyl, hexyl, heptyl, octyl, nonyl and/or decyl groups.

Polymer (ii) preferably comprises apolyorganohydrogensiloxane-polydiorganosiloxane copolymer, incorporatingone or more units ii-I and/or ii-II:

—O—Si R²H—O—  ii-I

—O—Si R² ₂H  ii-II

and one or more units ii-V and/or ii-VI:

—O—Si R² ₂—O—  ii-V

—O—Si R² ₃  ii-VI

wherein R² is as hereinbefore defined, more preferably copolymerincorporating polyorganohydrogensiloxane end-capping units, i.e polymerchains terminate with the group or moiety ii-VII:

≡Si—H,  ii-VII

more particularly with the unit of formula ii-II:

—O—Si R² ₂H  ii-II

as hereinbefore defined. Most preferably polymer (ii) comprisesmethylhydrogensiloxane-dimethylsiloxane copolymers.

Polymer (ii) may also comprises a polyorganosiloxane, exhibiting, permolecule, at least two hydrogen atoms bonded to the silicon andpreferably at least three ≡SiH units and having, for example, aviscosity of between 1 and 5000 mPa·s, that is to say between 0.001 and5 Pa·s, up to 300 Pa·s as hereinbefore defined, such that when combinedin Part B with further Part B components, Part B is of viscosity in arange as hereinbefore defined, which can in particular be formed ofsiloxyl units of formula:

$\begin{matrix}{H_{g}X_{i}{SiO}_{\frac{4 - g - i}{2}}} & (V)\end{matrix}$

in which:

-   -   X is a monovalent hydrocarbon group with no unfavorable effect        on the activity of the catalyst which is generally chosen from        alkyl groups having from 1 to 8 carbon atoms inclusive, such as        the methyl, ethyl, propyl and 3,3,3-trifluoropropyl groups,        cycloalkyl groups, such as the cyclohexyl, cycloheptyl and        cyclooctyl groups, and aryl groups, such as xylyl, tolyl and        phenyl,    -   g=1 or 2, preferably =1, i=0, 1 or 2 and g+i=1, 2 or 3,        optionally all the other units being units of average formula:

$\begin{matrix}{X_{j}{SiO}_{\frac{4 - j}{2}}} & ({VI})\end{matrix}$

-   -   in which X has the same meaning as above and j=0, 1, 2 or 3.

Examples of polymer (ii) are polymethylhydrosiloxanes ormethylhydrodimethylsiloxane copolymers.

In the case that polymers include other units additional to iIII, iIV,iiI and iiII for example, these are suitably not reactive with therespective polymer at ambient temperature or under sterilisingconditions.

Suitably the ratio of silicon-bonded hydrogen atoms provided by (ii) tosilicon-bonded alkenyl moieties provided by (i) is at least 0.5:1,preferably 1:1,

Preferably embodiments of the curable composition follow the catalysedaddition cure reaction according to the following scheme:

P^(i)—R^(Alk1)—CR^(Alk1)═CR^(Alk2) ₂+P^(ii)—SiHR²R^(2/P)→^([catalyst])

P^(i)—R^(Alk1)—CHR^(Alk1)CR^(Alk2) ₂—SiR²R^(2/P)P^(ii)

more preferably:

wherein integers are as hereinbefore defined and R^(1/P) is selectedfrom P^(i) and R¹ as hereinbefore defined and R^(2/P) is selected fromP^(ii) and R² as hereinbefore defined.

The polymers (i) and (ii) and catalyst (iii) may be apportioned in atleast one Part A and at least one Part B in manner to provide respectiveParts A and B which in isolation are not reactive at ambienttemperature, nor under sterilisation conditions, such as heat orradiation. Apportioning may also be determined according to volume andviscosity.

Polymers (i) and (ii) and catalyst (iii) may be apportioned in at leastone Part A and at least one Part B in manner such that polymer (ii) isabsent from Part A and polymer (i) is absent from Part B or Part Bincorporates a trace amount of polymer (i) represented as molar ratio(Si—H unit or moiety)/(alkenyl unit or moiety) of greater than or equalto 2000. Such composition may be sterilised at effective gamma orradiation dose for example as disclosed in WO2012/069794, the contentsof which are incorporated herein by reference.

The at least one Part A and at least one Part B may be of substantiallyequal volume and viscosity or of different volume and/or viscosity. PartA or Part B may incorporate a suitable viscosity moderator or diluent,in amount to increase or reduce volume and/or viscosity. By this meansPart A and Part B having different volume and viscosity may be volumeand viscosity matched for improved ease and intimacy of mixing anddispensing. A suitable diluent is for example a silicone oil which isavailable in any desired viscosity for thickening or thinning effect.Alternatively or additionally at least one Part A and at least one PartB are sealed in respective receptacles or on respective supports whichare thermally stable at an elevated temperature of 121° C. or more for aperiod of up to 28 hours, for example as disclosed in WO2012/069793, thecontents of which are incorporated herein by reference.

The composition may thereby be rendered terminally sterile by beingsterilised in its primary packaging and this property may becharacterised by a Sterility Assurance Level (SAL). The SAL is definedin ISO 11139:2006 as the probability of a single viable microorganismoccurring on an item after sterilization. The term SAL takes aquantitative value, in the format of 10^(−n), where typically n=3, 4, 5or 6, preferably SAL=10⁻³ or 10⁻⁶.

A catalyst as hereinbefore defined may be any catalyst which iseffective in catalysing the addition curing reaction as hereinbeforedefined, more preferably as hereinabove illustrated. Suitable catalystsare selected from any known form of platinum, rhodium, palladium, nickeland like addition curing hydrosilylation catalysts, for example asdisclosed in U.S. Pat. No. 5,153,231, US 2006/0217016, U.S. Pat. No.3,928,629 and U.S. Pat. No. 4,529,553 the contents of which areincorporated herein by reference.

A platinum catalyst may be selected from platinum black platinum asdeposited on carriers including silica such as silica gel or carbon suchas powdered charcoal, platinic chloride or chloroplatinic acid andalcohol solutions thereof, salts of platinic and chloroplatinic acidsand platinum complexes such as platinum/olefin,platinum/alkenylsiloxane, platinum/beta-diketone, platinum/phosphine andthe like. Chloroplatinic acid may be the hexahydrate or anhydrous form.A platinum complex may be prepared from chloroplatinic acid and itshexahydrate, or from platinous chloride, platinum dichloride, platinumtetrachloride and their neutralised complexes withdivinyltetramethyldisiloxane, optionally diluted withdimethylvinylsiloxy endcapped polydimethylsiloxane.

A palladium catalyst may be selected from palladium on carbon, palladiumchloride and the like.

A rhodium catalyst may be selected from rhodium chloride and one or morecomplexes of rhodium having the general formula iii-I or iii-II:

RhX₃(SR₂)₃  (iii-I)

Rh₂(CO)₄X₂  (iii-II)

wherein each X represents a halogen atom and each R represents an alkylor aryl radical or combination thereof having from 1 to 8 inclusivecarbon atoms or the R′₃SiQ group in which Q represents a divalentaliphatic hydrocarbon radical having from 1 to 6 inclusive carbon atomsand R′ represents an alkyl or aryl radical or combination thereof havingfrom 1 to 8 inclusive carbon atoms or a (CH₃)₃Si— group, not more thanone R′ per molecule being (CH₃)₃Si—. For example rhodiumchloride/di(n-butyl)sulfide complex and the like.

A nickel catalyst is preferably a zero valent nickel selected fromM₂Ni⁽⁰⁾ such as bis(1,5-cyclo-octadienyl)nickel (Ni(COD)₂) and fromMNi⁽⁰⁾G wherein M is a bidentate alkene cyclic hydrocarbon ring of C₈₋₁₂and G is selected from monodentate and bidentate phosphorous groupshaving hydrogen atoms, substituted or unsubstituted hydrocarbon radicalsor mixtures thereof bonded to the phosphorous atoms of the phosphorousgroups.

The composition may include a catalyst inhibitor. Suitable inhibitorsare known in the art. For example a catalyst inhibitor may be selectedfrom a polymethylvinylsiloxane cyclic compound and an acetylenicalcohol, such as methyl butynol for example as in Cavi-Care or disclosedin U.S. Pat. No. 5,153,231, the contents of which are incorporatedherein by reference.

Preferably the composition comprises an addition-reaction retardant or acrosslinking inhibitor chosen, for example, from the followingcompounds:

-   -   polyorganosiloxanes substituted with at least one alkenyl that        may optionally be in cyclic form, tetramethylvinyltetrasiloxane        being particularly preferred,    -   organic phosphines and phosphites,    -   unsaturated amides,    -   alkyl maleates, and    -   acetylenic alcohols.

These acetylenic alcohols (see FR-A-1 528 464 and FR-A-2 372 874), whichare among the preferred thermal blockers of the hydrosilylationreaction, have the formula:

(R′)(R″)C(OH)—C≡CH

in which formula

-   -   R′ is a linear or branched alkyl radical, or a phenyl radical;    -   R″ is H or a linear or branched alkyl radical, or a phenyl        radical; the radicals R′, R″ and the carbon atom alpha to the        triple bond possibly forming a ring; and    -   the total number of carbon atoms contained in R′ and R″ being at        least 5 and preferably from 9 to 20.        Examples that may be mentioned include:

-   1-ethynyl-1-cyclohexanol;

-   3-methyl-1-dodecyn-3-ol;

-   3,7,11-trimethyl-1-dodecyn-3-ol;

-   1,1-diphenyl-2-propyn-1-ol;

-   3-ethyl-6-ethyl-1-nonyn-3-ol;

-   2-methyl-3-butyn-2-ol;

-   3-methyl-1-pentadecyn-3-ol.

These α-acetylenic alcohols are commercial products. Such a retardant ispresent in a maximum proportion of 3000 ppm relative to the total weightof the polyorganosiloxanes in the silicone composition. Methyl butynolcould be chosen as in Cavi-Care.

The composition may be non-foamable or may be foamable, comprising (iv)an expansion or “blowing” agent, selected from any agent which evolvesgas or vapour as part of or during the curing reaction, for exampleselected from H-donors, OH-containing agents, H-bonding agents such as:

-   -   alcohols including methanol, ethanol, n-propanol, isopropanol,        n-butanol, 2-butanol, tert-butanol, n-hexanol, n-octanol and        benzyl alcohol. n-Propanol, n-butanol, n-hexanol and n-octanol        are particularly preferred,    -   polyols such as diols including, 4-butanediol, 1,5-pentanediol        and 1,7 heptanediol,    -   silane or polysilane having at least one silanol group, or    -   water.

The composition forms, after hydrosilylation, a silicone elastomer whichmay be foamed or have gel properties. A foamed composition does nottransmit air through the body of the foam or through the foam surface orboth, for example incorporates cells closed either by chemical ormechanical means. The term “silicone gel” denotes a crosslinked siliconeproduct characterized by a degree of penetration of, for example,between 20 and 500 tenths of a mm (measured by ASTM D 2137 penetrometry,weight of the rod and of the cone: 62.5 g).

When the composition is prepared for a silicone gel it may have at leastone nonfunctionalized polyorganosiloxane comprising:

-   -   a) end siloxyl units of type M=(R⁶)₃SiO_(1/2)        in which the R⁶ radicals which are identical or different,        correspond to an optionally substituted linear or branched C1-C₆        alkyl group and/or a substituted or unsubstituted aryl group,        and    -   b) identical or different siloxyl units of type D=(R⁷)₂SiO_(2/2)        in which the R⁷ radicals correspond to the same definition as        R⁶.

The physical properties of these gels are adjusted according to the useby varying the levels of siloxyl units carrying Si-alkenyl and SiHfunctional groups and when it is present by varying the percentage byweight of nonfunctionalized polyorganosiloxane, which is well known inthe prior art.

To enhance the adhesive properties of a silicone gel, the compositionmay further comprise a monofunctional polyorganosiloxane carrying asingle Si-alkenyl group per molecule as taught by European patentapplication EP-1633830-A2.

Further, a composition may also comprise inorganic filler such asreinforcing or bulking fillers. These fillers can be provided in theform of very finely divided products, the mean particle diameter ofwhich is less than 0.1 μm. These fillers include in particular fumedsilicas and precipitated silicas; their specific surface is generallygreater than 10 m²/g and generally lies within the range 20-300 m²/g.

These fillers can also be provided in the form of more coarsely dividedproducts, with a mean particle diameter of greater than 0.1 μm. Mentionmay in particular be made, as examples of such fillers, of groundquartz, calcium carbonate, diatomaceous silicas, calcined clay, titaniumoxide of the rutile type, iron, zinc, chromium, zirconium or magnesiumoxides, the various forms of alumina (hydrated or nonhydrated), boronnitride, lithopone or barium metaborate; their specific surfaces aregenerally less than 30 m²/g.

The filler may have a hydrophobic surface, which may be obtained bytreating the filler, e.g. with suitable silanes, short chain siloxanes,fatty acids or resinous silicone materials.

Hexamethyldisilazane treated fumed silica may be considered, or iftranslucence is to be maintained, vinyl “Q” reinforcing resins may beused. A filler may be hydroplobic. Suitable materials and processes forrendering the surface of fillers hydrophobic have been described in theliterature, and are known to the person skilled in the art. The fillerscan also be composed of a mixture of several types of fillers withdifferent particle sizes.

The composition may comprise a thixotropic agent. A thixotropic agentconfers on a composition properties whereby it becomes viscous duringapplication and reverts to higher viscosity after application when nolonger being worked. Thixotropes include fillers such as silica, andcertain silicone-based substances.

A composition may include additional components including otheradjuvants, preservatives including propyl gallate, extenders, rheologyregulators, adhesion promoters or adhesion reducers, moisture vaporpermeability (MVP) or moisture vapor transmission rate (MVTR) promotersto prevent maceration of skin having composition applied thereto,whereby skin can transpire and pass liquid but still function as asealant and bacterial barrier, and the like. Suitably such additionalcomponents confer properties as hereinbefore defined on the composition.

The composition may comprise active agents, which may have any desiredactivity for the intended purpose, and include active pharmaceuticalingredients (API's) and the like.

Antimicrobial agents, biocides and disinfectants may be selected fromsilver, in particular nano crystalline silver, and derivatives includingsilver complexes and salts such as ionic silvers, silver zeolite, silveroxide, silver nitrate, silver acetate, silver chloride, silversulphadiazine), biguanides including polyhexamethylene biguanide,chlorhexidine digluconate and its acetate salts chlorhexidine acetateand diacetate, manuka honey, peroxides (e.g. hydrogen peroxide), iodine(e.g. povidone iodine), sodium hypochlorite, copper, copper complexes;zinc (e.g. zinc oxide, zinc pyrithione), gold, gold complexes;phosphates, amines, amides and sulphonamides (e.g. hexamidine,proflavine, mafenide, nitrofurazone, norfloxacin); antibiotics (e.g.gentamicin, bacitracin, rifampicin; alcohols and acids (e.g. ethanol,phenoxy ethanol, mupirocin).

Nutrients, pain killers and other pain management techniques suitablyinclude analgesics and anesthetics and may be selected from amethocaine,lignocaine, non-steroidal anti-inflammatory drugs, anti inflammatoriessuch as hydrocortisone, paraffin to reduce adherence to the skin, ureato reduce dehydration of the skin; buffering components to promotehealing of the skin.

Heamostats may be selected from chitin, chitosan, kaolin;antifibrinolytics such as amino acids, aminocaproic acid, tranexamicacid, aminomethylbenzoic acid; Proteinase inhibitors includingaprotinin, alfa1 antitrypsin, C1-inhibitor, camostat; Vitamin K andother hemostatics including vitamin K, phytomenadione, menadione;fibrinogen including human fibrinogen; local hemostatics includingabsorbable gelatin sponge, oxidized cellulose, tetragalacturonic acidhydroxymethylester, adrenalone, thrombin, collagen, calcium alginate,epinephrine; blood coagulation factors including coagulation factor IX,II, VII and X in combination, coagulation factor VIII, factor VIIIinhibitor bypassing activity, coagulation factor IX, coagulation factorVII, von Willebrand factor and coagulation factor VIII in combination,coagulation factor XIII, eptacog alfa (activated), nonacog alfa,thrombin and systemic hemostatics: etamsylate, carbazochrome, batroxobinromiplostim, eltrombopag.

Active agents may further include combination materials includingsuperabsorbers, odour management agents, wovens and non wovens, gellablefibres; growth factors, wound debridements—mechanical, autolytic andenzymatic; resorbable dressings and micro structure to influence cellingrowth; cells, tissue (e.g. autologous treatments); indicators; dyesand colourants and coloured indicators, whiteners such as zinc oxide andtitanium oxide.

The composition may be in a form that it may be dispensed in any knownmanner, such as by pallet knife, syringe, static mixer, roll-onapplicator, spray, wipe, brush, foam, sponge, non-woven, part integratedor fully integrated into dressing, or manually applied. An applicatorusing a sponge is demonstrated with Chloraprep i.e.http://www.chloraprep.co.uk. For a two part curing system that requiresmixing, a static mixer such as a double barreled syringe with a mixinghead may be used.

Preferably therefore the curable two part composition is provided as atleast one Part A and at least one Part B sealed in or on respectivereceptacles or supports suitable for cooperatively dispensing from acooperative dispensing device, preferably sealed in respective barrelsor respective cassettes for a static mixer such as a double barrelsyringe, more preferably provided together with a cooperating dispensingdevice such as a static mixer.

More preferably a syringe with a nozzle to allow insertion of materialinto exposed transmission layer, or a spreader tip to allow spread ofmaterial across the severed transmission layer edge, or a combinationthereof (spreader having plural projecting apertures) may be used (e.g.Double-Syringe Prefilled Delivery System (L-System), Medmix Systems Ag,fitted with static mixer and spreader tiphttp://lwww.medmix.ch/L-SYSTEM.html).

For certain embodiments there is a clear advantage in using anapplicator with an integral spreader. Where material is applied directlyto the severed dressing edge, particularly in the case of an extendedsevered edge, it is advantageous to manipulate this material to ensureoptimal placement. An integral spreader minimises cross contaminationwhen the sealant is manipulated. During the manipulation crosscontamination could relate to: contamination of the sealant with amicrobiological burden, contamination of the sealant with foreignbodies, contamination of the sealant with chemicals (such chemicals mayhave an influence on the sealant) and contamination of personnel orequipment with the sealant. For other embodiments there is advantage inusing an applicator without a spreader, for example for filling bodycrevices etc.

Where the composition is a curing system chemical contamination mayadversely affect the cure process. For example where the composition isa platinum catalysed RTV-2 silicone, contact with latex or nitrilecontaining gloves may affect the curing. The problem caused by theexample given has been documented in the dental press with regards tothe delayed setting of polyvinyl siloxane dental impression materialswhen mixed with certain types of glove (Y. Walid, Z. AI-Ani and R. Gray,Silicone impression materials and latex gloves. Is interaction fact orfallacy?, Dent Update, 2012, 39, pp.:39-42).

In a medical setting an integral applicator with spreader thereforeovercomes the obstacle of a clinician being unable to use a glovedfinger (subject to the chemical composition of the glove) to manipulatethe sealant, overcomes the possibility of using an ungloved finger, thuseliminating direct hand to patient contact (not only would this approachbe inappropriate for most clinical settings, it would likely result withtransfer of the curing composition to the clinician's fingertip) andovercomes the requirement to contaminate any other medical devices orimplements with the curing composition.

Dispensing may be by means of syringe or static mixer having a nozzlehead comprising a combination of spreader tip with plural nozzles ashereinbefore and hereinbelow defined, for example a spreader havingplural projecting apertures. Preferably a nozzle head comprises 2 to 10nozzles for example 3 to 6 nozzles such as 3 or 5 nozzles. Nozzlespreferably have low aperture to dispense sealant to the interior portionwithin the exposed portion of transmission layer. For example the spreadof the nozzle head may match the width of the bridging portion enablingdispensing on a single insertion. This embodiment of dispenser for andmode of dispensing composition benefits from a decreased burden anddecreased requirement for accuracy on the part of the operator, anincrease in mechanical accuracy of dispensing location and continuousseal formation. It may also slightly reduce the back-pressure at thesyringe allowing the use of higher viscosity composition. A substantialborder region as hereinbefore defined may contribute to seal integrity.

Preferably a nozzle head has moderate width or spread of head fordispensing into exposed portion of a transmission layer on a curve, e.g.a body contour, for example having from 2 to 4 nozzles, such as 2 or 3nozzles. An alternative multi nozzle head is flexible or deformable intwo locations facilitating dispensing into exposed portion of atransmission layer on a curve, e.g. a body contour and/or dispensinginto a location having obstructed access. Such nozzle head comprises aflexible arm or restraint through which the plural nozzles emerge. Thearm is joined to the main nozzle head and thereby to releasably to thestatic mixer, optionally via flexible tubes. The arm may be bent toconform to an arc. The tubes may similarly be bent to conform togenerate an angled nozzle. The tubes may beneficially increasing theentry angle for dispensing.

The flexible arm is typically not elastic, i.e. it retains the shapeconferred for dispensing until bent to return to its original shape or adifferent conformation. The flexible arm could be formed of a deformablepolymer or putty or the like or it could be a mechanical flexible ordeformable arm (i.e. http://snakeclamp.com/orhttp://joby.com/gorillapod).

Preferably a dispenser has low profile and can be contained within animaginary cone. This dictates the maximum dimensions that mayadvantageously be considered in the design of the dispenser to allow ashallow entry angle relative to the skin to allow a nozzle to beinserted into an exposed portion of transmission layer in a dressingadhered to a patient.

Preferably the sealant is a TNP sealant which generates or enhances afluid-tight, preferably an air-tight, seal. In one embodiment acomposition comprises a RTV-2 silicone such as Silpuran 2445™ which mayoptionally be modified to have viscosity as hereinbefore defined.Modification of viscosity is as known in the art and is suitably byincorporating filler such as for example fumed silica or optionallytranslucent filler or resin or reinforcing resin as hereinbeforedefined, to achieve the hereinbefore defined viscosity, or by combiningParts A and B and allowing to pre-react to the hereinbefore definedviscosity before application, or the like. Increasing cure rate is asknown in the art, for example increasing the amount of catalyst orreducing the amount of catalyst inhibitor present, if any.

Method of Preparation

A further aspect is the preparation of a composition as hereinbeforedefined. Methods for preparing non-curing or curable compositions ashereinbefore defined in 1 or more Parts are known in the art. Preferablythe method comprises loading composition or respective parts thereofinto an applicator or cassettes therefore as hereinbefore defined.

A further aspect is a method for preparing a curable composition ashereinbefore defined comprising the steps of:

combining polymers (i) and (ii) and catalyst (iii) as hereinbeforedefined to form at least one Part A and at least one Part B; in mannersuitable for cooperatively dispensing, for example for cooperativelydispensing from a double barrel syringe.

Method of Sterilisation

A further aspect is a method of sterilising the curable composition ashereinbefore defined comprising heating the one or more parts, forexample the at least one Part A and at least one Part B sealed inrespective thermally stable receptacles or supports at an elevatedtemperature of 121° C. or more for a period of up to 28 hours, or byirradiating wherein in the case of a 2 part curable composition thepolymers (i) and (ii) and catalyst (iii) are apportioned in at least onePart A and at least one Part B in manner such that polymer (ii) isabsent from Part A and polymer (i) is absent from Part B or Part Bincorporates a trace amount of polymer (i) represented as molar ratio(Si—H unit or moiety)/(alkenyl unit or moiety) of greater than or equalto 2000 with a radiation source selected from the group consisting ofgamma, x-ray, and e-beam radiation in effective sterilising dose.

Device

A further aspect is in the form of a device suitable for use in thefield of woundcare, comprising a dispensing device having one or pluralbarrel(s) or cassette(s), advancing means and optional mixing means,said barrel(s) or cassette(s) comprising the composition as hereinbeforedefined, in the case of a two or more part composition such that Parts Aand B are contained in respective barrels or cassettes, the devicehaving means for contacting respective Parts.

Preferably optional mixing means, contacting means and/or advancingmeans are provided integral with or separate from the device. Mixingmeans may be static or active. The device may incorporate a dwellchamber for mixed Parts A and B to partially cure to higher viscositybefore being dispensed.

Preferably the device is disposable comprising integral barrel(s) orcassette(s).

Preferably the device comprises an applicator for applying compositioncomprising means to configure composition on application, for examplecomprising an applicator with nozzle or integral spreader or acombination thereof.

Preferably a device comprises a nozzle head comprising a combination ofspreader tip with plural nozzles as hereinbefore and hereinbelowdefined, for example a spreader having plural projecting apertures.Preferably a nozzle head comprises 2 to 10 nozzles for example 3 to 6nozzles such as 3 or 5 nozzles. Nozzles preferably have low aperture todispense sealant to the interior portion within the exposed portion oftransmission layer. For example the spread of the nozzle head may matchthe width of the bridging portion enabling dispensing on a singleinsertion. This embodiment of dispenser for and mode of dispensingcomposition benefits from a decreased burden and decreased requirementfor accuracy on the part of the operator, an increase in mechanicalaccuracy of dispensing location and continuous seal formation. It mayalso slightly reduce the back-pressure at the syringe allowing the useof higher viscosity composition. A substantial border region ashereinbefore defined may contribute to seal integrity.

Preferably a nozzle head has moderate width or spread of head fordispensing into exposed portion of a transmission layer on a curve, e.g.a body contour, for example having from 2 to 4 nozzles, such as 2 or 3nozzles. An alternative multi nozzle head is flexible or deformable intwo locations facilitating dispensing into exposed portion of atransmission layer on a curve, e.g. a body contour and/or dispensinginto a location having obstructed access. Such nozzle head comprises aflexible arm or restraint through which the plural nozzles emerge. Thearm is joined to the main nozzle head and thereby to releasably to thestatic mixer, optionally via flexible tubes. The arm may be bent toconform to an arc. The tubes may similarly be bent to conform togenerate an angled nozzle. The tubes may beneficially increasing theentry angle for dispensing.

The flexible arm is typically not elastic, i.e. it retains the shapeconferred for dispensing until bent to return to its original shape or adifferent conformation. The flexible arm could be formed of a deformablepolymer or putty or the like or it could be a mechanical flexible ordeformable arm (i.e. http://snakeclamp.com/orhttp://joby.com/gorillapod).

Preferably a dispenser has low profile and can be contained within animaginary cone. This dictates the maximum dimensions that mayadvantageously be considered in the design of the dispenser to allow ashallow entry angle relative to the skin to allow a nozzle to beinserted into an exposed portion of transmission layer in a dressingadhered to a patient.

In a further embodiment there is provided a novel device as hereinbeforedefined comprising a nozzle head comprising a combination of spreadertip with plural nozzles as hereinbefore and hereinbelow defined, forexample a spreader having plural projecting apertures. Preferably anozzle head comprises 2 to 10 nozzles for example 3 to 6 nozzles such as3 or 5 nozzles. Further features are as hereinbefore described.

If required these systems may be used together with a suitableskin-compatible sealant at the perimeter as defined in PCTGB2012/000866.

A dressing as hereinbefore defined may be any wound dressing, preferablyis a wound dressing having a Si wound contact surface, more preferablyis a TNP dressing, optionally modified to comprise a perimeter region ashereinbefore defined. Known TNP dressings include: Smith & NephewDisposable Kits for TNP such as Smith & Nephew, RENASYS-F/AB, AbdominalDressing Kit; Smith & Nephew, RENASYS-F/P, Foam Dressing Kit With Port;Smith & Nephew, RENASYS-G, Gauze Dressing Kit; Smith & Nephew, PICO™dressing kit; and KCI Kits for TNP including, V.A.C.™ GranuFoamDressings Kits; and the like. Additional dressings and methods oftreating wounds with negative pressure are disclosed in the followingapplications that are hereby incorporated by reference: U.S. applicationSer. No. 13/381,885, filed 30 Dec. 2011 and published as US2012/0116334;U.S. application Ser. No. 12/886,088, filed 20 Sep. 2010 and publishedas US2011/0213287; U.S. application Ser. No. 13/092,042, filed 21 Apr.2011 and published as US2011/0282309; U.S. application Ser. No.12/744,277, filed 20 Sep. 2010 and published as US2011/0028918; and U.S.application Ser. No. 12/744,218, filed 20 Sep. 2010 and published asUS2011/0054421, also WO2011/000622, WO 2011i000621, WO2011/135285,WO2011/135286, U.S. Pat. No. 7,964,766 and U.S. Pat. No. 7,615,036 (allSmith & Nephew) the contents of which are incorporated herein byreference. Conventional TNP dressings are applied with a drape placedthereover, of which the second face is air-tight.

Such dressings can additionally comprise a tissue (wound) contact layer,a negative pressure distribution and transmission layer and an optionalwound exudate absorbing layer as hereinbefore defined.

Preferably the composition is dispensed to a composite TNP dressing suchas the PICO™ dressing. A composite dressing incorporates an integralair-tight backing layer (also referred to herein as a wound cover ordrape), that may be made of a gas impermeable membrane and integral TNPtherapy layers, such as one or more negative pressure transmission ordistribution layers, a tissue (wound) contact layer, an absorbentmaterial layer such as a wound exudate absorbing layer or acquisitiondistribution layer (ADL) any of these optionally including asuperabsorbent polymer (SAP), said layers positioned beneath the backinglayer, and the backing layer or wound cover optionally allowstranspiration or liquid evaporation from wound exudate, as for examplewith the PICO™ dressing.

For example, one or more transmission layers or other layers may bepositioned or enclosed between a backing layer and an optional woundcontact layer. The transmission layer(s) may be in turn enclosed betweenthe backing layer and (optional wound contact layer and) a wound siteover which the dressing is configured to be positioned, for examplesealed therebetween. The composite dressing may be supplied togetherwith a number of adhesive strips comprised of drape material or may omitsuch strips with sealing by means of a sealant as disclosed inPCT/GB2012/000866, the contents of which are incorporated herein byreference.

The composition may therefore be applied to any dressing which it isdesired to cut to size or shape or to profile or articulate. Cutting issimply by removing the excess portion and retaining the required portionincluding negative pressure port.

Preferably the composition is dispensed to a trimmable dressing, havinga main dressing portion in fluid (gas) communication with additionaldressing portions or cells. One or more additional portions or cells maybe removed to provide a dressing having size or shape or profile orarticulation to be compatible with a wound or wound site to be dressed.Preferably portions or cells may be retained to provide a large surfacearea, or elongate, dressing to dress a similarly large surface area orelongate wound, or portions or cells may be removed to dress acorrespondingly reduced surface area or reduced length wound; preferablyone or more additional portions or cells may be conformed to provide ashaped dressing to dress a similarly shaped wound or to dress a woundincorporating or adjacent a protrusion such as a fixation device, forexample a pin, or such as a body part such as a digit; preferably one ormore additional portions or cells may be conformed to provide a profileddressing to dress a similarly profiled wound or wound site, such as awound located on complex body topography; preferably one or moreadditional portions or cells may be articulated to dress a similarlyarticulated wound or wound site such as a wound located on a joint.

In an advantage the composition may be used to seal a trimmable dressingas disclosed in U.S. Provisional Application Ser. No. 61/800,040, filedMar. 15, 2013, titled “WOUND DRESSING AND METHOD OF TREATMENT,” thecontents of which are incorporated herein directly and by reference.

A trimmable dressing is preferably a wound treatment apparatus fortreatment of a wound site comprising:

-   -   a backing layer having an upper surface and a lower surface and        defining a perimeter configured to be positioned over skin        surrounding a wound site;    -   a transmission layer configured to be positioned below the        backing layer; and    -   one or more ports configured to transmit negative pressure        through the backing layer for the application of topical        negative pressure at the wound site;    -   wherein the apparatus comprises a plurality of cells or regions        separated by one or more trimmable portions. Trimmable        portion(s) may be bridging portions as hereinbefore defined.

In some embodiments, the plurality of cells forms a plurality ofrepeating negative pressure treatment modules.

In one embodiment, one or more of the modules can be removed and theremoved module(s) can subsequently be used to provide negative pressureto the wound site. In another embodiment, one or more modules can beremoved and the remaining module(s) can subsequently be used to providenegative pressure to the wound site. In further embodiments, thetrimmable portions may have a maximum width of 50 mm (or approximately50 mm), 40 mm (or approximately 40 mm), 30 mm (or approximately 30 mm),20 mm (or approximately 20 mm), or even 15 mm (or approximately 15 mm).In some embodiments, the trimmable portion may be from 10 mm to 20 mm(or approximately 10 mm to approximately 20 mm). The one or moretrimmable portions may comprise one or more bridging portions having asmaller width as compared to the width of an adjacent cell or region.For example, the bridging portion may have a maximum width of ⅛, ¼, or ⅓(or approximately ⅛, ¼, or ⅓) of a width of an adjacent cell or region.The plurality of cells or regions may comprise an absorbent material,the absorbent material positioned between the transmission layer and thebacking layer. The one or more trimmable portions may comprise anabsorbent material, the absorbent material positioned between thetransmission layer and the backing layer. In other embodiments, noabsorbent material is positioned between the transmission layer and thebacking layer. Some embodiments may further comprise an acquisitiondistribution layer having a similar footprint to the transmission layer,the acquisition distribution layer configured to be positioned above thetransmission layer. The apparatus is preferably as further hereinbelowdefined.

Exposed portion(s) as hereinbefore defined are the result of removing aportion of the wound dressing, which may be by any envisaged means, forexample cutting the wound dressing or tearing along a weakened line.Composite wound dressings may comprise a border for affixing around awound, about a central wound contact portion. The dressing ashereinbefore defined may include a backing layer and wound contact layerof similar footprint or surface area to the transmission layer or otherlayers enclosed therebetween, for example is a borderless dressing) orof greater footprint or surface area than the transmission layerenclosed therebetween (for example is a bordered dressing). Exposedportion(s) as hereinbefore defined result from removing a portion of thewound dressing as hereinbefore defined directly enclosing thetransmission layer or other layers, for example by cutting into orthrough the backing layer and wound contact layer and the transmissionlayer therebetween.

Embodiments of dressings described herein address the problem ofproviding dressings in a range of sizes or shapes to accommodateirregularly shaped wounds or body topography, for example vein harvestwound dressings accommodating variations in height and leg-length ofindividuals, the provision of which is impractical both to themanufacturer and to the user. Embodiments enhance adaptability ofexisting dressings, including more recently introduced multisitedressings such as trilobes and quadrilobes. Certain embodiments enable aportion of a dressing to be removed to create a main wound dressing ofdesired size or shape or profile or articulation, and sealing exposedportion(s) thereof to contain a negative pressure.

The portion(s) of the wound dressing may be removed to size the mainwound dressing portion for positioning over a wound as hereinbeforedefined, for example an incisional wound, an elongate leg wound, anarcuate incisional wound and the like. Similarly the portion(s) of thewound dressing may be removed to shape the main wound dressing portionfor positioning over a wound as hereinbefore defined, such as a flapwound, about a protruding device such as a fixation device or aprotruding body part, to profile the main wound dressing for positioningover a wound as hereinbefore defined, for example on complex bodytopography, or to articulate the main wound dressing for positioningover a wound as hereinbefore defined for example on a flexing joint. Thewound treatment apparatus may be rolled into a tape which can be cutalong the one or more bridging portions. Cutting along the bridgingportion may sever adjacent cells.

The composition may alternatively be advantageously dispensed to seal adressing for treatment of a wound site comprising:

-   -   a backing layer having an upper surface and a lower surface        otherwise a backing sheet as hereinbefore termed and defining a        perimeter configured to be positioned over skin surrounding a        wound site;    -   a transmission layer configured to be positioned beneath the        backing layer; or otherwise positioned at or on one side of one        face of the backing sheet and    -   a plurality of ports configured to transmit negative pressure        spaced apart on the backing layer.

The wound treatment apparatus may be configured to be rolled into atape. The plurality of ports each may comprise an opening in the backinglayer covered with a releasable tab. The transmission layer may compriseone or more bridging portions having a smaller width than adjacentportions of the transmission layer. A negative pressure may beestablished at a wound site by means of any one of the plurality ofports, the remainder of which may remain sealed or may be removed with asection of dressing. The wound treatment apparatus may be used in anydesired length by cutting between adjacent ports.

In above dressings, the wound treatment apparatus further comprises anoptional wound contact layer, with the transmission layer(s) positionedbetween the backing layer and the wound contact layer. The transmissionlayer(s) may be in direct or indirect contact with a lower surface ofthe backing layer. In some embodiments, the one or more transmissionlayers comprise a first layer comprising a spacer material configured tovertically wick fluid. The one or more transmission layers may furthercomprise a second layer comprising an acquisition distribution materialconfigured to horizontally wick fluid, the second layer positioned abovethe first layer. One of the first layer and the second layer, or both,may be present in the one or more bridging portions. In otherembodiments, the one or more transmission layers comprise an acquisitiondistribution material configured to horizontally wick fluid. In someembodiments, the port may comprise an opening in the backing layer. Theport may comprise a port member attached to the backing layer over anopening in the backing layer. The port member may be sealed to the uppersurface of the backing layer. Some embodiments may further comprise anabsorbent material between the backing layer and the transmission layerhaving a similar footprint to that of the transmission layer(s).Absorbent material may be present or absent in bridging portion(s) ashereinbefore defined. Some embodiments of the one or more transmissionlayers may further comprise an acquisition distribution layer betweenthe backing layer and the optional wound contact layer and thetransmission layer and/or absorbent layer having a similar footprint tothat of the absorbent material and/or absorbent layer. The one or moretransmission layers may further comprise a spacer material configured todistribute negative pressure, the spacer material having a similarfootprint to the acquisition distribution material, the spacer materialconfigured to be positioned beneath the acquisition distributionmaterial. Acquisition distribution layer or material may be present orabsent in bridging portion(s) as hereinbefore defined. The acquisitiondistribution material may be provided as the transmission material orlayer

The transmission layer (hereinafter layer(s)) may have a rectangularshape having a longitudinal axis extend along its length. Thetransmission layer may comprise one or more bridging portions centeredon the longitudinal axis. The transmission layer may comprise three ormore bridging portions centered on the longitudinal axis. The one ormore bridging portions may also be offset from the longitudinal axis.The one or more bridging portions may have a width that is less than ⅓the width of adjacent portions of transmission layer. The one or morebridging portions may have a width that is less than ¼ the width ofadjacent portions of transmission layer. The one or more bridgingportions may have a width that is less than ⅛ the width of adjacentportions of transmission layer. As is used herein, a smaller widthrepresents a narrowing of or neck or constriction in transmission layerwith respect to adjacent portions thereof. The transmission layer mayhave a T-shape with a bridging portion on each leg of the T. Thetransmission layer may have a T-shape with at least one bridging portionon each leg of the T. The transmission layer may comprise a plurality ofcells each separated by one or more bridging portions. The transmissionlayer may comprise a plurality of cells, and wherein each of theplurality of cells is connected to at least one adjacent cell by one ormore bridging portions, preferably the bridges provide for gascommunication between adjacent cells.

Some embodiments may further comprise a fluidic connector configured tosupply negative pressure to the port. Some embodiments may furthercomprise a source of negative pressure configured to supply negativepressure through the port. Negative pressure may be established at awound site by means of any one of the plurality of ports, or by means ofmultiple ports of the plurality of ports, the remainder of which mayremain sealed or may be removed with a section of dressing. Someembodiments may further comprise one or more separate or integraladhesive strips or sealing strips. Strips are configured to retain andseal the backing layer to skin surrounding a wound after the apparatusis cut along or across the one or more bridging portions, i.e betweenadjacent cells or ports. Strips may be comprised of backing layermaterial, such as polyurethane or hydrocolloid, or silicone basedmaterial such as OPSITE^(⋄) FLEXIFIX^(⋄) or OPSITE^(⋄) FLEXIFIX^(⋄)Gentle.

In a further aspect there is provided a novel apparatus as hereinbeforedefined. Accordingly there is provided a wound treatment apparatus fortreatment of a wound site comprising:

-   -   a backing layer having an upper surface and a lower surface and        defining a perimeter configured to be positioned over skin        surrounding a wound site;    -   a transmission layer configured to be positioned below the        backing layer; and    -   one or more ports configured to transmit negative pressure        through the backing layer for the application of topical        negative pressure at the wound site;    -   wherein the apparatus comprises a plurality of cells or regions        separated by one or more trimmable portions. Features are as        hereinbefore defined.

The one or more ports may each comprise an opening in the backing layercovered with a releasable tab, and negative pressure may be applied tothe backing layer through at least one of the openings. Some embodimentsmay comprise multiple ports configured to transmit negative pressurethrough the backing layer, each port corresponding to a separatenegative pressure treatment module. Some embodiments may furthercomprise a wound contact layer configured to be positioned beneath thetransmission layer, the wound contact layer further configured to sealto the backing layer around the perimeter.

In some embodiments, the plurality of cells may be approximately thesame size, approximately square, and configured in a grid. In otherembodiments, the plurality of cells may be configured in a T-shape. Inother embodiments, the plurality of cells may be configured into a roll.In other embodiments, the plurality of cells may be configured in alinear arrangement. In some embodiments, each of the plurality of cellsmay be configured with one of the one or more ports. In otherembodiments, at least two of the plurality of cells may be eachconfigured with one of the one or more ports. The apparatus may furthercomprise a source of negative pressure connected to some or all of theone or more ports. In some embodiments, the dressing may comprise anexposed portion of transmission layer. The exposed portion may be sealedwith a sealant or adhesive material. The apparatus is preferably asfurther hereinbefore defined.

In some embodiments, the at least one material layer of the firstportion comprises one or more of a transmission layer such asreticulated open-cell foam, woven material, non-woven material, 3D knitfabric, Baltex 7970 weft knitted polyester, acquisition distributionmaterial, DryWeb TDL2, SlimCore TL4, or the like. The at least onematerial of the first portion can additionally or alternatively comprisean absorbent layer, for example a superabsorbent pad comprisingcellulose fibers and superabsorbent particles, MH460.101, ALLEVYN™ foam,Freudenberg 114-224-4, or Chem-Posite™ 11C-450. In some embodiments, thebridging portion comprises at least one material layer comprising one ormore of-eticulated open-cell foam, woven material, non-woven material,3D knit fabric, Baltex 7970 weft knitted polyester, acquisitiondistribution material, DryWeb TDL2, SlimCore TL4, or the like. In someembodiments, the at least one material layer of the bridging portionshould transmit a negative pressure of at least −40 mmHg against a setpoint in the range −60 to −200 mmHg with an air leak of 50 cc/minute. Insome embodiments, the at least one material layer of the bridgingportion should experience a pressure differential of approximately −25mmHg or less (that is, closer to zero) at a set point of −200 mmHg withan air leak of 50 cc/minute over an approximately 20 mm±1 mm distance.In other embodiments, the at least one material layer of the bridgingportion should experience a pressure differential of approximately −5mmHg or less (that is, closer to zero) at a set point of −200 mmHg withan air leak of 50 cc/minute over an approximately 20 mm±1 mm distance.In some embodiments, the at least one material layer of the bridgingportion has a height, in an uncompressed state, of at least 1 mm (orapproximately 1 mm), at least 3 mm (or approximately 3 mm), at least 4mm (or approximately 4 mm), or at least 5 mm (or approximately 5 mm),and a width of at least 1 mm (or approximately 1 mm), or at least 2 mm(or approximately 2 mm), at least 3 mm (or approximately 3 mm), at least4 mm (or approximately 4 mm), or at least 5 mm (or approximately 5 mm).In some embodiments, the at least one material layer of the bridgingportion has a maximum height, in an uncompressed state, of 9 mm (orapproximately 9 mm) for purposes of being more easily re-sealable whencut. In some embodiments in which the dressing is sealed with a sealant,the at least one material layer can be resilient to compression suchthat a height of a sealed portion, in a compressed state, issubstantially the same as the height of the sealed portion in anuncompressed state. In one embodiment, the at least one material layerof the bridging portion comprises a spacer material having a height ofat least 2 mm (or approximately 2 mm) and a width of at least 1 mm (orapproximately 1 mm). In one embodiment, the at least one material layerof the bridging portion comprises a reticulated open-cell foam having aheight of at least approximately 5 mm and a width of at leastapproximately 3 mm, which, when wet, may experience a pressuredifferential of −8.9 (or approximately −8.9) mmHg. In anotherembodiment, the at least one material layer of the bridging portioncomprises an acquisition distribution layer (e.g., SlimCore TL4) havinga height of at least approximately 2 mm and a width of at leastapproximately 4 mm. Such dimensions can represent an uncompresseddimension of the material layer of the bridging portion. In oneembodiment, the at least one material layer of the bridging portion isnot compressible.

We have found that a composition when dispensed to seal a dressing inmanner as hereinbefore defined, may provide an advantageous seal inrelation to an exposed trimmed portion or bridging portion comprisingmaterial layer(s) which undergo no change or substantially no change incompressibility on initiation of negative pressure, i.e. is resilient toor substantially resilient to compression induced by negative pressure,or which undergo a substantially similar compression to or lessercompression than the composition seal, on initiation of negativepressure, i.e is substantially equally resilient or less resilient thanthe composition seal to compression induced by negative pressure. Inparticular in relation to a curing or hardening system, this relativecompressibility is in relation to the cured elastomer or hardened seal.Preferably a composition forms a seal which is compressible to touch inrelation to material layer(s) which are substantially non-compressibleor compressible to a lesser degree, on initiation of negative pressure,than the seal. Preferably the one or more trimmable portions or bridingportions comprise material substantially resilient to the application ofnegative pressure, preferably the bridging portion(s) have height whichis substantially unchanged on the application of negative pressure,preferably having height which is reduced by less than or equal to 10%,more preferably 8%, most preferably 5%, on the application of negativepressure. This ensures a smooth surface to the dressing and minimaldiscomfort provided to the wearer, if negative pressure is applied aftersealing the dressing, and also ensures that the seal remains intact andis not ruptured if negative pressure is applied before sealing thedressing and is subsequently temporarily interrupted.

In some embodiments, the bridging portion comprises the same layer(s) asthe first portion. In other embodiments, the bridging portion comprisesfewer layers than the first portion. In some embodiments, the layer(s)in the bridging portion have a smaller width than the layer(s) in thefirst portion. In some embodiments, the layer(s) in the bridging portionhave a dimension that is smaller than the layer(s) in the first portion(for example, the individual or combined height of the layer(s) in thebridging portion is smaller than the height of the layer(s) in the firstportion. In other embodiments, the layer(s) in the bridging portion havethe same width as the layer(s) in the first portion. In someembodiments, the bridging portion connects the first portion to anadjacent portion having a similar layered construction and/or width asthe first portion. In some embodiments, there are multiple bridgingportions that may connect a first portion to multiple adjacent portions,or may connect between multiple adjacent portions.

Kit and Components Thereof

A further aspect is a kit for use in the field of wound care comprisinga dressing for overlying a wound and skin thereabout which may be cut tosize or shape as hereinbefore defined together with a composition ashereinbefore defined.

Some kits comprise a vacuum pump.

In a particular advantage, the kit, sealant composition and/or dressingor wound cover may be terminally sterile. Techniques are known forsterilising apparatus, such as dry heat, steam, radiation and the like.GB1020005.3, GB 1019997.4 and GB1104512.7 disclose terminallysterilisable 2 part compositions and methods for their sterilisation.Methods include heat sterilisation and radiation sterilisation, inparticular gamma, e-beam or x-ray radiation sterilisation. Preferablythe sealant is terminally sterilisable or sterile and is sterilizedprior to dispensing by heating the first and second parts in a thermallystable receptacle or support at an elevated temperature of 121° C. ormore for a period of up to 28 hours, or by irradiating the first andsecond parts with a radiation source selected from the group consistingof gamma, x-ray, and e-beam radiation with a dose that provides aneffective sterility assurance level.

A further aspect is a method for dispensing or releasing, and curing acomposition as hereinbefore defined, comprising dispensing into adesired location at curing temperature for curing time.

The composition may be manually mixed and dispensed. Alternatively anyform of dispensing device may be employed, for example the compositionmay be dispensed by means of a cooperative dispensing devicecooperatively dispensing, for example by means of a double barrelsyringe, for example by activating respective barrels of a double barrelsyringe, or loading respective cassettes therefore and activating.

A further aspect is an elastomer comprising a cured composition ashereinbefore defined,

Method of Use

A further aspect is a method for dispensing a composition ashereinbefore defined comprising:

optionally combining Parts A and B of a curable composition ashereinbefore defined thereby initiating cure; dispensing compositioninto a location as hereinbefore defined;after a suitable period an optionally elastomeric seal is formed.

A further aspect is a method for sealing a woundcare dressingcomprising:

cutting a dressing to size or shape;positioning the dressing overlying a wound and skin thereabout;optionally combining Parts A and B of a curable composition ashereinbefore defined thereby initiating cure;dispensing composition into a location as hereinbefore defined;after a suitable period an optionally elastomeric seal is formed at thesevered dressing edge.

Preferably the composition is dispensed by means of a syringe forexample a cooperative dispensing device as hereinbefore definedcooperatively dispensing, for example by means of a double barrelsyringe, for example by activating respective barrels of a double barrelsyringe, or loading respective cassettes therefore and activating,preferably wherein the syringe incorporates integral means to configurethe dispensed sealant, for example an integral spreader head.

Method of Treatment

A further aspect is a method for sealing a dressing or for treating awound site, of a human or animal subject in need thereof comprising:

-   -   dressing the wound site with a dressing, as hereinbefore        defined, exposing a portion thereof as hereinbefore defined and    -   dispensing a composition as hereinbefore defined.

Preferably the method comprises:

-   -   providing a wound dressing as hereinbefore defined comprising:    -   a backing layer; and    -   a transmission layer positioned beneath the backing layer,    -   removing a portion of the wound dressing to create a main wound        dressing portion with one or more exposed portions;    -   positioning the main wound dressing portion over a wound;    -   sealing the main wound dressing to skin surrounding the wound,        and further sealing further sealing the one or more exposed        portions of the main wound dressing portion; and    -   applying negative pressure to the wound through the backing        layer of the main wound dressing portion.

In some embodiments of the method, removing a portion of the wounddressing comprises cutting the wound dressing across at least one of theone or more bridging portions. At least a portion of the wound dressingmay comprise pre-cut score marks to facilitate removing of the portionof wound dressing. The dressing may comprise a plurality of openings inthe backing layer covered with a releasable tab, and negative pressuremay be applied to the backing layer through one of the openings. Thedressing may comprise a plurality of openings in the backing layercovered with a releasable tab, and negative pressure may be applied tothe backing layer through two or more of the openings.

The portions of the wound dressing may be removed to size the main wounddressing portion for positioning over an incisional wound. The portionsof the wound dressing may be removed to size the main wound dressingportion for positioning over an elongate leg wound. The portions of thewound dressing may be removed to size the main wound dressing portionfor positioning over an arcuate incisional wound.

In another embodiment, a method of treating a wound is provided,comprising:

-   -   providing a wound dressing comprising a backing layer, a        transmission layer beneath the backing layer, and a plurality of        spaced apart openings in the backing layer each covered with a        releasable tab, the wound dressing configured into a length or        roll;    -   optionally unrolling a portion of the wound dressing from the        roll;    -   removing a portion of the wound dressing from the length or        roll, the removed portion comprising at least one opening in the        backing layer covered with a releasable tab;    -   positioning the removed portion of the wound dressing over a        wound; and    -   applying negative pressure through at least one opening in the        backing layer after a releasable tab has been removed.

Preferably dispensing a sealant composition is by means of a device ashereinbefore defined.

Preferably the dressing is adhered over the wound site with at least anadhesive underside of the dressing or an adhesive disposed on at leastan underside of the dressing.

Preferably the method further comprises adjusting the position of thedressing before the composition is dispensed.

Preferably the sealant is dispensed after dressing the wound site withthe dressing.

Preferably the wound dressing is adapted to contain a negative pressure,the method additionally comprising applying negative pressure to thewound site using a source of negative pressure connected to the woundsite.

Preferably applying negative pressure is conducted before and afterdispensing sealant.

Preferably applying negative pressure is by means of a portable negativepressure source in fluid communication with the wound dressing locatedover a wound site.

Preferably the method includes monitoring transmitted negative pressureat the wound against generated negative pressure.

Preferably a dressing is a combination TNP therapy dressingincorporating fluid-tight backing layer, functional wound therapy layersand an integral attachment for a negative pressure source, preferably aportable and/or periodic negative pressure source by means of whichnegative pressure is applied to the wound site through or under thebacking layer. Preferably an aperture is created into or under the drapeso as to connect the wound site to the source of negative pressure.

A wound packing material may be located so as to partially or completelyfill the wound site.

Providing the sealant may be by means of dispensing a sealantcomposition as hereinbefore defined by the method as hereinbeforedefined.

The method may include monitoring transmitted negative pressure againstgenerated negative pressure. This may be used to provide the user withfeedback during the dressing application. Typically NP is monitored atthe pump, or alternatively at end of port.

Preferably the dressing is applied, the NP source activated, pump downinitiated, detecting for alarms indicating NP loss, rub down dressing toclose off any sites of NP loss, apply sealant at severed edges.

In an advantage, providing the sealant is by means of dispensing asealant composition, wherein the composition is a fluid that whendispensed forms a material capable of making a substantially fluid-tightseal.

Preferably the method comprises combining at least two pre-polymers toform the sealant.

Preferably the dressing is part of a portable NPWT system. The exudateis managed in a portable canister or within the dressing. The negativepressure source is portable or may be connected intermittently.Preferably the skin contact layer is an adhesive silicone gel, otheradhesive or combination of adhesive silicone gel and other adhesive.

Portable composite TNP dressings are commercially available and includePrevena (KCI), NPD1000 NP wound Therapy System (Kalypto Medical Inc),PICO (Smith & Nephew), amongst others, and are more extensivelydescribed in the literature, for example in PCT/GB2011/000629, thecontents of which are incorporated herein by reference.

Upon the application of negative pressure with the pump, the dressingmay in some embodiments partially collapse and present a wrinkledappearance as a result of the evacuation of some or all of the airunderneath the dressing. In some embodiments, the pump may be configuredto detect if any leaks are present in the dressing, such as at theinterface between the dressing and the skin surrounding the wound site.Should a leak be found, such leak is preferably remedied prior tocontinuing treatment.

Treatment of the wound site preferably continues until the wound hasreached a desired level of healing. In some embodiments, it may bedesirable to replace the dressing after a certain time period haselapsed, or if the dressing is full of wound fluids. During suchchanges, the pump may be kept, with just the dressing being changed.

A further aspect provides the use of a composition, kit or apparatus ashereinbefore defined for dressing wounds, preferably for negativepressure wound therapy dressing of wounds as hereinbefore defined. Thesealant composition, kit and apparatus may be useful for example insealing medical dressings, for example in restraining egress of woundexudate or ingress of air or infection, in addition to providing avacuum seal for TNP application.

Such use includes use on wounds selected from chronic, acute, traumatic,sub-acute and dehisced wounds, ulcers (such as pressure or diabetic),partial-thickness burns and flaps and grafts. These include open, moist,granulating wounds, preferably surgical wounds such as those resultingfrom excision of ulcers, cancerous tissue such as perianal and perinealwounds and the like. For optimum healing of such wounds, the woundshould be prevented from closing in on itself and allowing fluids toaccumulate, whilst at the same time allowing the tissue around the woundto progressively contract, and the wound to shrink. Wound fillingmaterials in NPWT therefore function as a type of “stent”, supportingthe wound and holding it open.

A sealant composition, kit or apparatus is particularly suited for usein clean, aseptic or sterile applications. Preferably the composition,kit or apparatus is rendered sterile, as known in the art or ashereinbefore defined, and packaged within barrier means. Further barriermeans provide a barrier to infection, whereby the composition, kit orapparatus is a double wrapped item, this allows for the removal of thefirst layer of sterile sealed packaging to reveal receptacles orsupports such as cartridges for or incorporated in a syringe, adhesivestrips and the like, which are completely sterile inside and out,facilitating entry into a sterile environment. The composition omittinga further barrier means would comprise a non-sterile external surface ofreceptacles or supports and associated barrier means. If it is notpossible to sterilise the composition using standard conditions formedical apparatus as hereinbefore described, it may not be possible totake such a composition into a sterile field.

A sealant for medical dressings may be applied in any known or novelmanner. WO 00/74738 (Guyuron) discloses use of silicone based RTV-2compositions to seal wounds i.a to minimise potential infections. Thesealant may suitably therefore be used by casting on top of the woundand surrounding skin and allowing to cure.

A further aspect provides the medical use of a kit, sealant or apparatusas hereinbefore defined.

Embodiments have one or more of the following advantages:

Allows severed dressing edges to be sealed readily.

Sealing of 3-dimensional dressing perimeters following complex bodycontours enhancing the ability to remove or reduce leaks.

Sealing of custom sized, shaped, contoured, articulated dressings.

Sealing of dressings where the borders conform to body geometries withtight external radii or are otherwise subject to high levels ofdeformation.

Sealing of systems where the dressing will be subject to a great deal ofmovement (e.g. neck, shoulder, underarm, elbow, forearm, wrist, hand,groin, knee, ankle, heel, foot).

A number of specific embodiments are given hereinbelow, appropriate forconventional Advanced Wound Dressings, conventional NPWTDrapes/Dressings or PICO™ and a sealant as hereinbefore defined. Generalreferences hereinbelow are however not to be construed as limiting tothe specific figure or embodiment which they are intended to illustrate,rather for the sake of avoiding undue duplication such description maybe present in the following section although of equal or greaterrelevance and equally pertinent to the foregoing.

FIG. 1 illustrates an embodiment of a TNP wound treatment system 100comprising a wound dressing 110 in combination with a pump 150. Asstated above, the wound dressing 110 can be any wound dressingembodiment disclosed herein including without limitation dressingembodiment or have any combination of features of any number of wounddressing embodiments disclosed herein. Here, the dressing 110 may beplaced over a wound as described previously, and a conduit 130 may thenbe connected to the port 120, although in some embodiments the dressing101 may be provided with at least a portion of the conduit 130preattached to the port 120. Preferably, the dressing 110 is provided asa single article with all wound dressing elements (including the port120) pre-attached and integrated into a single unit. The wound dressing110 may then be connected, via the conduit 130, to a source of negativepressure such as the pump 150. The pump 150 can be miniaturized andportable, although larger conventional pumps may also be used with thedressing 110.

In some embodiments, the pump 150 may be attached or mounted onto oradjacent the dressing 110. A connector 140 may also be provided so as topermit the conduit 130 leading to the wound dressing 110 to bedisconnected from the pump, which may be useful for example duringdressing changes.

FIGS. 2A-D illustrates the use of an embodiment of a TNP wound treatmentsystem being used to treat a wound site on a patient. FIG. 2A shows awound site 200 being cleaned and prepared for treatment. Here, thehealthy skin surrounding the wound site 200 is preferably cleaned andexcess hair removed or shaved. The wound site 200 may also be irrigatedwith sterile saline solution if necessary. Optionally, a skin protectantmay be applied to the skin surrounding the wound site 200. If necessary,a wound packing material, such as foam or gauze, may be placed in thewound site 200. This may be preferable if the wound site 200 is a deeperwound.

After the skin surrounding the wound site 200 is dry, and with referencenow to FIG. 2B, the wound dressing 110 may be positioned and placed overthe wound site 200. Preferably, the wound dressing 110 is placed withthe wound contact layer 2102 over and/or in contact with the wound site200. In some embodiments, an adhesive layer is provided on the lowersurface 2101 of the wound contact layer 2102, which may in some cases beprotected by an optional release layer to be removed prior to placementof the wound dressing 110 over the wound site 200. Preferably, thedressing 110 is positioned such that the port 2150 is in a raisedposition with respect to the remainder of the dressing 110 so as toavoid fluid pooling around the port. In some embodiments, the dressing110 is positioned so that the port 2150 is not directly overlying thewound, and is level with or at a higher point than the wound. To helpensure adequate sealing for TNP, the edges of the dressing 110 arepreferably smoothed over to avoid creases or folds.

With reference now to FIG. 2C, the dressing 110 is connected to the pump150. The pump 150 is configured to apply negative pressure to the woundsite via the dressing 110, and typically through a conduit. In someembodiments, and as described above in FIG. 1, a connector may be usedto join the conduit from the dressing 110 to the pump 150. Upon theapplication of negative pressure with the pump 150, the dressing 110may, in some embodiments, partially collapse and present a wrinkledappearance as a result of the evacuation of some or all of the airunderneath the dressing 110. In some embodiments, the pump 150 may beconfigured to detect if any leaks are present in the dressing 110, suchas at the interface between the dressing 110 and the skin surroundingthe wound site 200. Should a leak be found, such leak is preferablyremedied prior to continuing treatment.

Turning to FIG. 2D, additional fixation strips 210 may also be attachedaround the edges of the dressing 110. Such fixation strips 210 may beadvantageous in some situations so as to provide additional sealingagainst the skin of the patient surrounding the wound site 200. Forexample, the fixation strips 210 may provide additional sealing for whena patient is more mobile. In some cases, the fixation strips 210 may beused prior to activation of the pump 150, particularly if the dressing110 is placed over a difficult to reach or contoured area.

Treatment of the wound site 200 preferably continues until the wound hasreached a desired level of healing. In some embodiments, it may bedesirable to replace the dressing 110 after a certain time period haselapsed, or if the dressing is full of wound fluids. During suchchanges, the pump 150 may be kept, with just the dressing 110 beingchanged.

FIGS. 3A-C illustrates cross-sections through a wound dressing 2100similar to the wound dressing of FIG. 1 according to an embodiment ofthe disclosure. A view from above the wound dressing 2100 is illustratedin FIG. 1 with the line A-A indicating the location of the cross-sectionshown in FIGS. 3A and 3B. The wound dressing 2100, which canalternatively be any wound dressing embodiment disclosed hereinincluding without limitation wound dressing 110 or any combination offeatures of any number of wound dressing embodiments disclosed herein,can be located over a wound site to be treated. The dressing 2100 may beplaced to as to form a sealed cavity over the wound site. In a preferredembodiment, the dressing 2100 comprises a backing layer 2140 attached toa wound contact layer 2102, both of which are described in greaterdetail below. These two layers 2140, 2102 are preferably joined orsealed together so as to define an interior space or chamber. Thisinterior space or chamber may comprise additional structures that may beadapted to distribute or transmit negative pressure, store wound exudateand other fluids removed from the wound, and other functions which willbe explained in greater detail below. Examples of such structures,described below, include a transmission layer 2105 and an absorbentlayer 2110.

As illustrated in FIGS. 3A-C, a lower surface 2101 of the wound dressing2100 may be provided with an optional wound contact layer 2102. Thewound contact layer 2102 can be a polyurethane layer or polyethylenelayer or other flexible layer which is perforated, for example via a hotpin process, laser ablation process, ultrasound process or in some otherway or otherwise made permeable to liquid and gas. The wound contactlayer 2102 has a lower surface 2101 and an upper surface 2103. Theperforations 2104 preferably comprise through holes in the wound contactlayer 2102 which enable fluid to flow through the layer 2102. The woundcontact layer 2102 helps prevent tissue ingrowth into the other materialof the wound dressing. Preferably, the perforations are small enough tomeet this requirement while still allowing fluid to flow therethrough.For example, perforations formed as slits or holes having a size rangingfrom 0.025 mm to 1.2 mm are considered small enough to help preventtissue ingrowth into the wound dressing while allowing wound exudate toflow into the dressing. In some configurations, the wound contact layer2102 may help maintain the integrity of the entire dressing 2100 whilealso creating an air tight seal around the absorbent pad in order tomaintain negative pressure at the wound.

Some embodiments of the wound contact layer 2102 may also act as acarrier for an optional lower and upper adhesive layer (not shown). Forexample, a lower pressure sensitive adhesive may be provided on thelower surface 2101 of the wound dressing 2100 whilst an upper pressuresensitive adhesive layer may be provided on the upper surface 2103 ofthe wound contact layer. The pressure sensitive adhesive, which may be asilicone, hot melt, hydrocolloid or acrylic based adhesive or other suchadhesives, may be formed on both sides or optionally on a selected oneor none of the sides of the wound contact layer. When a lower pressuresensitive adhesive layer is utilized may be helpful to adhere the wounddressing 2100 to the skin around a wound site. In some embodiments, thewound contact layer may comprise perforated polyurethane film. The lowersurface of the film may be provided with a silicone pressure sensitiveadhesive and the upper surface may be provided with an acrylic pressuresensitive adhesive, which may help the dressing maintain its integrity.In some embodiments, a polyurethane film layer may be provided with anadhesive layer on both its upper surface and lower surface, and allthree layers may be perforated together.

A layer 2105 of porous material can be located above the wound contactlayer 2102. This porous layer, or transmission layer, 2105 allowstransmission of fluid including liquid and gas away from a wound siteinto upper layers of the wound dressing. In particular, the transmissionlayer 2105 preferably ensures that an open air channel can be maintainedto communicate negative pressure over the wound area even when theabsorbent layer has absorbed substantial amounts of exudates. The layer2105 should preferably remain open under the typical pressures that willbe applied during negative pressure wound therapy as described above, sothat the whole wound site sees an equalized negative pressure. The layer2105 may be formed of a material having a three dimensional structure.For example, a knitted or woven spacer fabric (for example Baltex 7970weft knitted polyester) or a non-woven fabric could be used.

A layer 2110 of absorbent material is provided above the transmissionlayer 2105. The absorbent material, which comprise a foam or non-wovennatural or synthetic material, and which may optionally comprise asuper-absorbent material, forms a reservoir for fluid, particularlyliquid, removed from the wound site. In some embodiments, the layer 2100may also aid in drawing fluids towards the backing layer 2140.

With reference to FIGS. 3A-C, a masking or obscuring layer 2107 can bepositioned beneath at least a portion of the backing layer 2140. In someembodiments, the obscuring layer 2107 can have any of the same features,materials, or other details of any of the other embodiments of theobscuring layers disclosed herein, including but not limited to havingany viewing windows or holes. Additionally, the obscuring layer 2107 canbe positioned adjacent to the backing layer, or can be positionedadjacent to any other dressing layer desired. In some embodiments, theobscuring layer 2107 can be adhered to or integrally formed with thebacking layer. Preferably, the obscuring layer 2107 is configured tohave approximately the same size and shape as the absorbent layer 2110so as to overlay it. As such, in these embodiments the obscuring layer2107 will be of a smaller area than the backing layer 2140.

The material of the absorbent layer 2110 may also prevent liquidcollected in the wound dressing 2100 from flowing freely within thedressing, and preferably acts so as to contain any liquid collectedwithin the absorbent layer 2110. The absorbent layer 2110 also helpsdistribute fluid throughout the layer via a wicking action so that fluidis drawn from the wound site and stored throughout the absorbent layer.This helps prevent agglomeration in areas of the absorbent layer. Thecapacity of the absorbent material must be sufficient to manage theexudates flow rate of a wound when negative pressure is applied. Sincein use the absorbent layer experiences negative pressures the materialof the absorbent layer is chosen to absorb liquid under suchcircumstances. A number of materials exist that are able to absorbliquid when under negative pressure, for example superabsorber material.The absorbent layer 2110 may typically be manufactured from ALLEVYN™foam, Freudenberg 114-224-4 and/or Chem-Posite™11C-450. In someembodiments, the absorbent layer 2110 may comprise a compositecomprising superabsorbent powder, fibrous material such as cellulose,and bonding fibers. In a preferred embodiment, the composite is anairlaid, thermally-bonded composite.

An orifice 2145 is preferably provided in the backing layer 2140 toallow a negative pressure to be applied to the dressing 2100. A suctionport 2150 is preferably attached or sealed to the top of the backinglayer 2140 over an orifice 2145 made into the dressing 2100, andcommunicates negative pressure through the orifice 2145. A length oftubing 2220 may be coupled at a first end to the suction port 2150 andat a second end to a pump unit (not shown) to allow fluids to be pumpedout of the dressing. The port may be adhered and sealed to the backinglayer 2140 using an adhesive such as an acrylic, cyanoacrylate, epoxy,UV curable or hot melt adhesive. The port 2150 is formed from a softpolymer, for example a polyethylene, a polyvinyl chloride, a silicone orpolyurethane having a hardness of 30 to 90 on the Shore A scale. In someembodiments, the port 2150 may be made from a soft or conformablematerial, for example using the embodiments described below in FIGS.3A-B.

Preferably the absorbent layer 2110 and the obscuring layer 2107 includeat least one through hole 2146 located so as to underlie the port 2150.The through hole 2146, while illustrated here as being larger than thehole through the obscuring layer 2107 and backing layer 2140, may insome embodiments be bigger or smaller than either. Of course, therespective holes through these various layers 2107, 2140, and 2110 maybe of different sizes with respect to each other. As illustrated inFIGS. 3A-C a single through hole can be used to produce an openingunderlying the port 2150. It will be appreciated that multiple openingscould alternatively be utilized. Additionally should more than one portbe utilized according to certain embodiments of the present disclosureone or multiple openings may be made in the absorbent layer and theobscuring layer in registration with each respective port. Although notessential to certain embodiments of the present disclosure the use ofthrough holes in the super-absorbent layer may provide a fluid flowpathway which remains unblocked in particular when the absorbent layer2100 is near saturation.

The aperture or through-hole 2146 is preferably provided in theabsorbent layer 2110 and the obscuring layer 2107 beneath the orifice2145 such that the orifice is connected directly to the transmissionlayer 2105. This allows the negative pressure applied to the port 2153to be communicated to the transmission layer 2105 without passingthrough the absorbent layer 2110. This ensures that the negativepressure applied to the wound site is not inhibited by the absorbentlayer as it absorbs wound exudates. In other embodiments, no aperturemay be provided in the absorbent layer 2110 and/or the obscuring layer2107, or alternatively a plurality of apertures underlying the orifice2145 may be provided.

The backing layer 2140 is preferably gas impermeable, but moisture vaporpermeable, and can extend across the width of the wound dressing 2100.The backing layer 2140, which may for example be a polyurethane film(for example, Elastollan SP9109) or hydrocolloid film, having a pressuresensitive adhesive on one side, is impermeable to gas and this layerthus operates to cover the wound and to seal a wound cavity over whichthe wound dressing is placed. In this way an effective chamber is madebetween the backing layer 2140 and a wound site where a negativepressure can be established. The backing layer 2140 is preferably sealedto the wound contact layer 2102 in a border region 2200 around thecircumference of the dressing, ensuring that no air is drawn in throughthe border area, for example via adhesive or welding techniques. Thebacking layer 2140 protects the wound from external bacterialcontamination (bacterial barrier) and allows liquid from wound exudatesto be transferred through the layer and evaporated from the film outersurface. The backing layer 2140 preferably comprises two layers; apolyurethane or hydrocolloid film and an adhesive pattern spread ontothe film. The film is preferably moisture vapor permeable and may bemanufactured from a material that has an increased water transmissionrate when wet.

The absorbent layer 2110 may be of a greater area than the transmissionlayer 2105, such that the absorbent layer overlaps the edges of thetransmission layer 2105, thereby ensuring that the transmission layerdoes not contact the backing layer 2140. This provides an outer channel2115 of the absorbent layer 2110 that is in direct contact with thewound contact layer 2102, which aids more rapid absorption of exudatesto the absorbent layer. Furthermore, this outer channel 2115 ensuresthat no liquid is able to pool around the circumference of the woundcavity, which may otherwise seep through the seal around the perimeterof the dressing leading to the formation of leaks.

As shown in FIG. 3A, one embodiment of the wound dressing 2100 comprisesan aperture 2146 in the absorbent layer 2110 situated underneath theport 2150. In use, for example when negative pressure is applied to thedressing 2100, a wound facing portion of the port 150 may thus come intocontact with the transmission layer 2105, which can thus aid intransmitting negative pressure to the wound site even when the absorbentlayer 2110 is filled with wound fluids. Some embodiments may have thebacking layer 2140 be at least partly adhered to the transmission layer2105. In some embodiments, the aperture 2146 is at least 1-2 mm largerthan the diameter of the wound facing portion of the port 2150, or theorifice 2145.

A filter element 2130 that is impermeable to liquids, but permeable togases is provided to act as a liquid barrier, and to ensure that noliquids are able to escape from the wound dressing. The filter elementmay also function as a bacterial barrier. Typically the pore size is 0.2μm. Suitable materials for the filter material of the filter element2130 include 0.2 micron Gore™ expanded PTFE from the MMT range, PALLVersapore™ 200R, and Donaldson™ TX6628. Larger pore sizes can also beused but these may require a secondary filter layer to ensure fullbioburden containment. As wound fluid contains lipids it is preferable,though not essential, to use an oleophobic filter membrane for example1.0 micron MMT-332 prior to 0.2 micron MMT-323. This prevents the lipidsfrom blocking the hydrophobic filter. The filter element can be attachedor sealed to the port and/or the backing layer 2140 over the orifice2145. For example the filter element 2130 may be molded into the port2150, or may be adhered to both the top of the backing layer 2140 andbottom of the port 2150 using an adhesive such as, but not limited to, aUV cured adhesive.

In FIG. 3B, an embodiment of the wound dressing 2100 is illustratedwhich comprises spacer elements 2152, 2153 in conjunction with the port2150 and the filter 2130. With the addition of such spacer elements2152, 2153, the port 2150 and filter 2130 may be supported out of directcontact with the absorbent layer 2110 and/or the transmission layer2105. The absorbent layer 2110 may also act as an additional spacerelement to keep the filter 2130 from contacting the transmission layer2105. Accordingly, with such a configuration contact of the filter 2130with the transmission layer 2105 and wound fluids during use may thus beminimized. As contrasted with the embodiment illustrated in FIG. 3A, theaperture 2146 through the absorbent layer 2110 and the obscuring layer2107 may not necessarily need to be as large o-larger than the port2150, and would thus only need to be large enough such that an air pathcan be maintained from the port to the transmission layer 2105 when theabsorbent layer 2110 is saturated with wound fluids.

With reference now to FIG. 3C, which shares many of the elementsillustrated in FIGS. 3A-C, the embodiment illustrated here comprises thebacking layer 2140, masking layer 2107, and absorbent layer 2110, all ofwhich have a cut or opening made therethrough which communicate directlyto the transmission layer 2105 so as to form the orifice 2145. Thesuction port 2150 is preferably situated above it and communicates withthe orifice 2145.

In particular for embodiments with a single port 2150 and through hole,it may be preferable for the port 2150 and through hole to be located inan off-center position as illustrated in FIGS. 3A-C and in FIG. 1. Sucha location may permit the dressing 2100 to be positioned onto a patientsuch that the port 2150 is raised in relation to the remainder of thedressing 2100. So positioned, the port 2150 and the filter 2130 may beless likely to come into contact with wound fluids that couldprematurely occlude the filter 2130 so as to impair the transmission ofnegative pressure to the wound site.

FIG. 4A illustrates an exploded view of a dressing 3400 for use innegative pressure wound therapy. Although this figure illustrates adressing having one particular shape, the construction of the layers canbe applied to any of the embodiments identified below, including FIGS.5A-8, and any of the dressing shapes and configurations described in thepatent applications incorporated by reference herein. The dressing 3400comprises a release layer 3480, wound contact layer 3460, a transmissionlayer 3450, an acquisition distribution layer 3440, an absorbent layer3430, an obscuring layer 3420, and a backing layer 3410. The dressing3400 may be connected to a port. At least the wound contact layer 3460,transmission layer 3450, absorbent layer 3430, obscuring layer 3420, andbacking layer 3410 may have properties as described with respect toparticular embodiments above, such as the embodiments of FIGS. 3A-C, aswell as or instead of the properties described below.

The dressing 3400 may comprise a wound contact layer 3460 for sealingthe dressing 3400 to the healthy skin of a patient surrounding a woundarea. Certain embodiments of the wound contact layer may comprise threelayers: a polyurethane film layer, a lower adhesive layer and an upperadhesive layer. The upper adhesive layer may assist in maintaining theintegrity of the dressing 3400, and the lower adhesive layer may beemployed for sealing the dressing 3400 to the healthy skin of a patientaround a wound site. As described above, in some embodiments withrespect to FIGS. 3A-C, some embodiments of the polyurethane film layermay be perforated.

Some embodiments of the polyurethane film layer and upper and loweradhesive layers may be perforated together after the adhesive layershave been applied to the polyurethane film. In some embodiments apressure sensitive adhesive, which may be a silicone, hot melt,hydrocolloid or acrylic based adhesive or other such adhesives, may beformed on both sides or optionally on a selected one side of the woundcontact layer. In certain embodiments, the upper adhesive layer maycomprise an acrylic pressure sensitive adhesive, and the lower adhesivelayer may comprise a silicone pressure sensitive adhesive. In otherembodiments the wound contact layer 3460 may not be provided withadhesive. In some embodiments, the wound contact layer 3460 may betransparent or translucent. The film layer of the wound contact layer3460 may define a perimeter with a rectangular or a square shape. Arelease layer 3480 may be removably attached to the underside of thewound contact layer 3460, for example covering the lower adhesive layer,and may be peeled off using flaps 3481. Some embodiments of the releaselayer 3480 may have a plurality of flaps extending along the length ofthe layer 3480.

Some embodiments of the dressing 3400 may comprise a spacer ortransmission layer 3450. The transmission layer 3450 may comprise aporous material or 3D fabric configured to allow for the passage offluids therethrough away from the wound site and into the upper layersof the dressing 3400. In particular, the transmission layer 3450 canensure that an open air channel can be maintained to communicatenegative pressure over the wound area even when the absorbent layer 3430has absorbed substantial amounts of exudates. The transmission layer3450 should remain open under the typical pressures that will be appliedduring negative pressure wound therapy as described above, so that thewhole wound site sees an equalized negative pressure.

Some embodiments of the transmission layer 3450 may be formed of amaterial having a three dimensional structure. For example, a knitted orwoven spacer fabric (for example Baltex 7970 weft knitted polyester) ora non-woven fabric can be used. In some embodiments, the transmissionlayer 3450 can have a 3D polyester spacer fabric layer. This layer canhave a top layer which is a 84/144 textured polyester, and a bottomlayer which can be a 100 denier flat polyester and a third layer formedsandwiched between these two layers which is a region defined by aknitted polyester viscose, cellulose or the like monofilament fiber. Inuse, this differential between filament counts in the spaced apartlayers tends to draw liquid away from the wound bed and into a centralregion of the dressing 3400 where the absorbent layer 3430 helps lockthe liquid away or itself wicks the liquid onwards towards the coverlayer 3410 where it can be transpired. Other materials can be utilized,and examples of such materials are described in U.S. Patent Pub. No.2011/0282309, which are hereby incorporated by reference and made partof this disclosure. However, the transmission layer 3450 may beoptional, and for example may be optional in embodiments of the dressing3400 which comprise the acquisition distribution layer 3440, describedbelow.

Some embodiments may comprise a wicking or acquisition distributionlayer (ADL) 3440 to horizontally wick fluid such as wound exudate as itis absorbed upward through the layers of the dressing 3400. Lateralwicking of fluid may allow maximum distribution of the fluid through theabsorbent layer 3430 and may enable the absorbent layer 3430 to reachits full holding capacity. This may advantageously increase moisturevapor permeation and efficient delivery of negative pressure to thewound site. Some embodiments of the ADL 3440 may comprise viscose,polyester, polypropylene, cellulose, or a combination of some or all ofthese, and the material may be needle-punched. Some embodiments of theADL 3440 may comprise polyethylene in the range of 40-150 grams persquare meter (gsm).

The dressing 3400 may further comprise an absorbent or superabsorbentlayer 3430. The absorbent layer can be manufactured from ALLEVYN™ foam,Freudenberg 114-224-4 and/or Chem-Posite™11C-450, or any other suitablematerial. In some embodiments, the absorbent layer 3430 can be a layerof non-woven cellulose fibers having super-absorbent material in theform of dry particles dispersed throughout. Use of the cellulose fibersintroduces fast wicking elements which help quickly and evenlydistribute liquid taken up by the dressing. The juxtaposition ofmultiple strand-like fibers leads to strong capillary action in thefibrous pad which helps distribute liquid.

For example, some embodiments of the absorbent layer 3430 may comprise alayered construction of an upper layer of non-woven cellulose fibers,superabsorbent particles (SAP), and a lower layer of cellulose fiberswith 40-80% SAP. In some embodiments, the absorbent layer 3430 may be anair-laid material. Heat fusible fibers can optionally be used to assistin holding the structure of the pad together. Some embodiments maycombine cellulose fibers and air-laid materials, and may furthercomprise up to 60% SAP. Some embodiments may comprise 60% SAP and 40%cellulose. Other embodiments of the absorbent layer may comprise between60% and 90% (or between about 60% and about 90%) celluose matrix andbetween 10% and 40% (or between about 10% and about 40%) superabsorbentparticles. For example, the absorbent layer may have about 20%superabsorbent material and about 80% cellulose fibers. It will beappreciated that rather than using super-absorbing particles or inaddition to such use, super-absorbing fibers can be utilized accordingto some embodiments of the present invention. An example of a suitablematerial is the Product Chem-Posite™ 11 C available from EmergingTechnologies Inc (ETi) in the USA.

Super-absorber particles/fibers can be, for example, sodium polyacrylateor carbomethoxycellulose materials or the like or any material capableof absorbing many times its own weight in liquid. In some embodiments,the material can absorb more than five times its own weight of 0.9%WAN/W saline, etc. In some embodiments, the material can absorb morethan 15 times its own weight of 0.9% W/W saline, etc. In someembodiments, the material is capable of absorbing more than 20 times itsown weight of 0.9% WAN/W saline, etc. Preferably, the material iscapable of absorbing more than 30 times its own weight of 0.9% W/WAsaline, etc. The absorbent layer 3430 can have one or more through holes3431 located so as to underlie the suction port.

Some embodiments of the present disclosure may optionally employ amasking or obscuring layer 3420 to help reduce the unsightly appearanceof a dressing 3400 during use due to the absorption of wound exudate.The obscuring layer 3420 may be a colored portion of the absorbentmaterial, or may be a separate layer that covers the absorbent material.The obscuring layer 3420 may be one of a variety of colors such as blue,orange, yellow, green, or any color suitable for masking the presence ofwound exudate in the dressing 3400. For example, a blue obscuring layer3420 may be a shade of blue similar to the shade of blue commonly usedfor the material of medical gowns, scrubs, and drapes. Some embodimentsof the obscuring layer 3420 may comprise polypropylene spunbondmaterial. Further, some embodiments of the obscuring layer 3420 maycomprise a hydrophobic additive or coating. Other embodiments maycomprise a thin fibrous sheet of 60, 70, or 80 gsm.

The obscuring layer may comprise at least one viewing window 3422configured to allow a visual determination of the saturation level ofthe absorbent layer. The at least one viewing window 3422 may compriseat least one aperture made through the obscuring layer. The at least oneviewing window 3422 may comprise at least one uncolored region of theobscuring layer. Some embodiments of the obscuring layer may comprise aplurality of viewing windows or an array of viewing windows.

The masking capabilities of the obscuring layer 3420 should preferablyonly be partial, to allow clinicians to access the information theyrequire by observing the spread of exudate across the dressing surface.An obscuring layer 3420 may be partial due to material propertiesallowing wound exudate to slightly alter the appearance of the dressingor due to the presence of at least one viewing window 3422 in acompletely obscuring material. The partial masking nature of theobscuring layer 3420 enables a skilled clinician to perceive a differentcolour caused by exudate, blood, by-products etc. in the dressingallowing for a visual assessment and monitoring of the extent of spreadacross the dressing. However, since the change in colour of the dressingfrom its clean state to a state with exudate contained is only a slightchange, the patient is unlikely to notice any aesthetic difference.Reducing or eliminating a visual indicator of wound exudate from apatient is likely to have a positive effect on their health, reducingstress for example.

The obscuring layer 3420 can have one or more through holes located soas to underlie the suction port. Some embodiments may have a maltesecross 3421 or other shaped cutout underlying the suction port, whereinthe diameter of the maltese cross 3421 is greater than the diameter ofthe port. This may allow a clinician to easily asses the amount of woundexudate absorbed into the layers beneath the port.

The dressing 3400 may also comprise a backing layer, or cover layer 3410extending across the width of the wound dressing. The cover layer 3410may be gas impermeable but moisture vapor permeable. Some embodimentsmay employ a polyurethane film (for example, Elastollan SP9109) or anyother suitable material. For example, certain embodiments may comprisetranslucent or transparent 30 gsm EU33 film. The cover layer 3410 mayhave a pressure sensitive adhesive on the lower side, thereby creating asubstantially sealed enclosure over the wound in which negative pressuremay be established. The cover layer can protect the wound as a bacterialbarrier from external contamination, and may allow liquid from woundexudates to be transferred through the layer and evaporated from thefilm outer surface.

The cover layer 3410 can have an orifice 3411 located so as to underliethe suction port. The orifice 3411 may allow transmission of negativepressure through the cover layer 3410 to the wound enclosure. The portmay be adhered and sealed to the cover film using an adhesive such as anacrylic, cyanoacrylate, epoxy, UV curable or hot melt adhesive. Someembodiments may have a plurality of orifices for the attachment ofmultiple ports or other sources of negative pressure or other mechanismsfor distributing fluid.

FIG. 4B illustrates a cross sectional view of the wound dressing 3400,displaying an embodiment of the relative thicknesses of layers of thedressing 3400. In some embodiments, the wound contact layer 3460 may beflat and the top film layer 3410 may be contoured over the inner layersof the dressing 3400. The spacer layer 3450 may be half as thick as theacquisition distribution layer 3440 in some embodiments. In someembodiments, the absorbent layer 3430 may be about 1.5 times thickerthan the spacer layer 3450. The obscuring layer 3420 may be about halfthe thickness of the spacer layer 3450.

FIG. 4C illustrates another embodiment of a wound dressing 3900, withthe various layers illustrated in an exploded view. Although this figureillustrates a dressing having one particular shape, the construction ofthe layers can be applied to any of the embodiments identified below,including FIG. 5A-FIG. 8, and any of the dressing shapes andconfigurations described in the patent applications incorporated byreference herein. The wound dressing may comprise a release layer 3980,wound contact layer 3960, a transmission layer 3950, an acquisitiondistribution layer 3940, an adhesive layer 3970, an absorbent layer3930, an obscuring layer 3920, and a backing layer 3910. At least thewound contact layer 3960, transmission layer 3950, absorbent layer 3930,obscuring layer 3920, and backing layer 3910 may have properties asdescribed with respect to particular embodiments above, such as theembodiments of FIGS. 3A-3C, as well as or instead of the propertiesdescribed below.

The dressing 3900 may be connected to a port 3990, as illustrated inFIG. 4D (shown without the release layer 3980). At least the backinglayer 3910, obscuring layer 3920, absorbent layer 3930, and acquisitiondistribution layer 3940 may have openings underlying the port 3990, andthe port 3990 may comprise a three-dimensional fabric 3997 and a filterelement 3995 overlying the openings. The absorbent layer 3930 may beconfigured to absorb and retain exudate from a patient's wound. Theabsorbent layer 3930 will preferably be constructed from a materialwhich has good absorbent qualities under negative pressure. The adhesivelayer 3970 may bond an upper surface of the acquisition distributionlayer 3940 to a lower surface of the absorbent layer 3930. In someembodiments of a trimmable dressing 3900, other layers may be bondedtogether to provide consistency with respect to layer alignment when thedressing is cut on one or more sides, such that the layers remaintogether when the sides of the dressing are cut, and such that there isnot vertical separation of the layers at the cut portions.

FIGS. A1-A4 illustrate trimming a TNP dressing in various manners. InFIG. A1, the cut line is a simple truncation of the dressing, exposingthe internal transmission layer; In FIG. A2, a hole has been cut toreceive a fixation device or digit; in FIG. A3, the dressing has beencut to allow profiling to a curved body portion; in FIG. A4 the dressinghas been articulated to dress a moving joint such as a knee, and in thiscase, transmission layer has been cut away but an amount of borderregion 2200 has been retained to assist in retaining and sealing thedressing at its edge.

FIGS. A5-A6 illustrate applying the trimmed dressings and dispensingsealant at the exposed transmission layer portions by means of syringeA. In FIG. A7. sealant is dispensed via syringe A to a puncture B in thebacking layer 2140.

FIG. B1 illustrates in detail the means of dispensing sealant by syringeA. The syringe in this case has a nozzle aperture which allows sealantto be dispensed within the structure of the transmission layer, in FIG.B2 a suitable relationship of transmission layer height or thickness andsyringe nozzle cross section and aperture is shown.

FIGS. C1-C3 illustrate different modes of dispensing sealant C:C1—internally to the transmission layer 2105, as was shown in FIG. B1;C2 and C2 a—bridging the exposed portion of transmission layer 2105 andskin surrounding a wound 200; and C3—bridging the exposed portion oftransmission layer 2105 and retention strips laid down on skinsurrounding a wound, before the dressing has been applied. Dressings areshown comprising backing layer or sheet and transmission layer, beingspacer layer, at the exposed portion 2105. The dressing may comprisefurther layer(s) (not shown) as hereinbefore defined at the exposedportion 2105. The main dressing portion or module of the dressing padmay contain further layers (e.g. an absorbent layer above thetransmission layer) not shown. FIG. C1 shows one embodiment of sealingand mode of dispensing of composition C. In this embodiment syringe Asuch as a static mixer is located such that the nozzle penetrates withinthe exposed portion 2105. The syringe A nozzle is of cross-section areasuited to be received within the exposed portion 2105 of transmissionlayer. Composition C is dispensed internally to the exposed portion2105. Syringe A nozzle is inserted to penetrate a short distance withinthe exposed portion 2105, at intervals along the exposed face, wherebycomposition C is dispensed internally as a seal within the exposedportion 2105. Composition may flow to some extent on initialapplication, either or both laterally to the direction of dispensing andadvancing and receding, flow becoming less as composition hardens orcures. This may aid in providing a continuous lateral seal, wherebydispensing intervals along the face of exposed portion 2105 may beincreased. Nozzle insertion distance within the exposed portion 2105 maybe selected to confine the seal spaced a short distance in from the faceof the exposed portion, or to allow some spill of composition C out ofthe exposed portion and onto surrounding surfaces such as a preparationplate or skin 200.

Advantages of this embodiment include minimizing the amount ofcomposition C required to be dispensed. This in turn allows use of alower capacity syringe or static mixer A. The back pressure encounteredon dispensing from a static mixer increases with the mixer volume, whichin turn leads to a decrease in the viscosity which the syringe or mixerA is able to dispense. It is generally advantageous to this embodimentto deliver composition C at as high a viscosity as possible to ensurethat composition C is confined within the exposed portion 2105. Afurther element in the total back pressure or resistance encountered ondispensing composition C is the nozzle aperture of syringe A. For thisembodiment, it is desired to dispense composition C from a smallaperture nozzle, and this adds to the back pressure. The advantage thatthis embodiment delivers of enabling a relatively small volume syringeor mixer A to be employed, allows greater freedom to operate a smallaperture nozzle.

Finally we have found that a seal generated by dispensing composition Cinternally to the exposed portion 2105, according to this embodiment, ishighly effective. The dressing should be trimmed, as hereinbeforedescribed, such that the exposed portion overlies intact skin about awound, and does not overly the wound itself. In the case of a dressinghaving an adhesive or tacky wound contact layer, such as a siliconecontact layer as hereinbefore described, the wound contact layer adheresto the skin 200 about the wound and seals the dressing to skin 200 aboutthe exposed portion 2105 and the dispensed seal C. The wound contactlayer is perforated or otherwise porous to allow transmission of fluidsto and from the wound bed, and this may permit flow of composition Conto skin directly proximal to the internal seal. This may beneficiallyenhance the seal between the wound contact layer and skin 200. In theevent that flow of composition to skin 200 directly proximal to theinternal seal is not desired, composition C suitably has a sufficientlyhigh viscosity to restrict flow, alternatively the wound contact layermay be non-porous or non-permeable in the region proximal to anenvisaged exposed portion, for example at a bridging portion ortrimmable portion as hereinbefore defined.

FIG. B1 may be considered, for one purpose, to illustrate dispensingcomposition C to a dressing having an obscuring layer whereby thedispensed seal is obscured. In contrast, the dispensed seal is shownbeneath the backing layer or sheet in FIG. C1. This illustrates thatdispensing composition C to a dressing having no obscuring layer, orhaving window(s) in obscuring layer at bridging portions or trimmableportion(s) allows visual control of nozzle insertion distance within theexposed portion 2105, of composition C volume dispensed, and of lateralflow enabling a suitable dispensing interval across the face of exposedportion 2105 to be determined. In the case that no obscuring layer ispresent it is preferred that the composition incorporates ADL ashereinbefore defined as transmission layer, rather than spacer layerwhich may pose a risk of penetrating the backing sheet. Figure C2 ashows an extension of FIG. C2 showing the sealant on the top film. Partsare referred to using the same reference numbering as in FIG. C2. Wehave found that an advantageous feature of a further embodiment ofsealing and mode of dispensing is that the composition C is dispensed tothe backing layer or backing sheet adjacent the exposed portion 2105,whereby composition C flows across the exposed portion 2105 totallycovering the exposed portion 2105. In some cases composition C flows ashort distance into or is drawn a short distance within the exposedportion 2105. It may be desired to dispense or smooth composition C ontothe perimeter of the exposed portion 2105 adjoining border region 2200as shown in FIG. C2 a, and even directed slightly back along theperimeter (not shown). This has the advantage of advancing composition Ca short distance at the perimeter of the exposed portion 2105, ensuringa total seal C and also securing the seal C in place. As composition Chardens or cures, the viscosity typically increases and flow ceaseswhereby composition C is retained at or in the dispensing location 2105and forms an effective seal C.

This further embodiment places performance requirements on thecomposition C and the resulting seal, additional to those of the firstembodiment of sealing and mode of dispensing. Specifically composition Crequires a continuous film to be dispensed and formed across the surfaceof the backing layer or sheet bridging onto the exposed portion of anyadditional layers and the exposed portion 2105 of the transmission layerand bridging onto the skin surface 200. Therefore composition C must besufficiently viscous and/or cohesive to form an intact film. Such filmmay be thin or, as illustrated in FIG. C2, C2 a and C3 may be ofappreciable depth and/or thickness of for example from the order ofdepth and/or thickness of the backing sheet to the order of depth and/orthickness of the dressing or of the component layers at the exposedportion 2105 thereof. Should such film rupture or fail prior to settingor curing of composition C then the seal will fail. After setting orcuring of an intact film, the exposed nature of the seal and itspresentation as a film place additional requirements of robustness, bothto external influences and also, to its ability to retain integrityacross interfaces between adjacent layers. These requirements are likelyto be greater in the case of a thin film. Preferably therefore a sealaccording to this further embodiment is characterized by properties oftensile strength, permanent set, and elongation at break, optionallyalso extensibility, in ranges as hereinbefore defined. In contrast aseal generated according to the first embodiment, as illustrated in FIG.C1 above, is supported in large part by the fabric of the dressingenclosing the seal C, whereby requirements of tensile strength,permanent set, elongation at break, are significantly lower, also beingenclosed within the lower extensibility dressing, the requirement forextensibility is significantly lower than for the further embodiment ofFIGS. C2 and C3.

FIGS. C2 a illustrates the need for the seal of this embodiment to beeffective from the backing layer surface across the exposed portion2105. As will be apparent, a seal across the exposed portion alone issusceptible to failure at the interface of the backing sheet and exposedportion and any intervening layers.

The further embodiment illustrated by FIGS. C2 to C3 is likely to bemore effective when adopted in relation to a dressing comprising noadditional layers as hereinbefore defined, thereby better resistingstrains introduced by separation at the interface of additional layer(s)and transmission layer. Additional layer(s) if present may beneficiallybe secured at their interfaces with each other and with transmissionlayer, by needling, stitching and other means as known in the art.

The further embodiment of FIGS. 2 and 3 moreover requires that a seal Chave low profile and/or compressibility greater than or equal to thesurrounding dressing. This is of advantage in minimizing discomfort tothe wearer imposed by a protruding ridge at the exposed portion 2105 ofthe dressing.

In FIGS. C4 and C5 syringe A is illustrated dispensing composition C toexposed portion 2105 of transmission layer in dressing, having borderregion 2200. In FIG. C6 syringe A is illustrated with modest nozzle headspread for dispensing composition C to profiled exposed portion 2105 oftransmission layer. In FIG. C7 syringe A nozzle head is illustratedhaving combined spreader tip with plural nozzles, conformable todispense to a profiled exposed portion and/or to dispense withobstructed access to exposed portion. In FIG. C8, an imaginary coneillustrates maximum dispenser A dimensions to allow a shallow entryangle to exposed portion 2105 relative to the skin 200.

FIGS. C4 and C5 illustrate dispensing composition C according to thefirst embodiment of sealing and mode of dispensing of composition C, ofFIG. C1, using a syringe or static mixer A having a combination ofspreader tip with plural nozzles as hereinbefore defined (spreaderhaving plural projecting apertures). Parts are referred to using thesame reference numbering as in FIG. C1. A dispenser (A) is illustratedhaving a nozzle head comprising 5 nozzles with small nozzle crosssection to deliver sealant to the interior portion within the exposedportion 2105 of transmission layer. The spread of the nozzle headmatches the width of the bridging portion shown enabling dispensing on asingle insertion. FIG. C4 illustrates internally dispensing compositionC to the interior portion of the exposed portion 2105 of a bridgingportion in the context of a relatively larger dressing. The maindressing portion or module of the dressing pad may contain furtherlayers (e.g. an absorbent layer above the transmission layer) not shown.FIG. C5 may for example illustrate dispensing to the interior portion ofthe exposed portion 2105 of a bridging portion in the context of anyshape or configuration dressing as hereinbefore defined. This embodimentof dispenser for and mode of dispensing composition benefits from adecreased burden and decreased requirement for accuracy on the part ofthe operator, an increase in mechanical accuracy of dispensing locationand continuous seal formation. It may also slightly reduce theback-pressure at the syringe allowing the use of higher viscositycomposition. A substantial border region 2200 is illustrated, whichcontributes to seal integrity.

FIG. C6 illustrates a multi nozzle head syringe A where the overallwidth or spread of the head is kept modest so as to allow dispensinginto exposed portion 2105 of a transmission layer on a curve, e.g. abody contour.

FIG. C7 illustrates an alternative multi nozzle head dispenser A that isflexible or deformable in two locations facilitating dispensing intoexposed portion 2105 of a transmission layer on a curve, e.g. a bodycontour and/or dispensing into a location 2105 having obstructed access.There is a flexible arm or restraint (shown in grey) with four nozzlesemerging out of the arm. This is joined to the main body (with integralstatic mixer) via four flexible tubes (also shown in grey).

The end on view illustrates the nozzle ends and flexible arm showing howthe arm may be bent to conform to an arc. The tubes may similarly bebent (not shown) to conform to generate an angled nozzle, beneficiallyincreasing the entry angle for dispensing.

The flexible arm is typically not elastic, i.e. it retains the shapeconferred for dispensing until bent to return to its original shape or adifferent conformation. The flexible arm could be formed of a deformablepolymer or putty or the like or it could be a mechanical flexible ordeformable arm (i.e. http://snakeclamp.com/orhttp://joby.com/gorillapod).

FIG. C8 illustrates an imaginary cone containing the dispenser A. Thisshows the maximum dimensions that may advantageously be considered inthe design of the dispenser A to allow a shallow entry angle relative tothe skin 200, to allow a nozzle to be inserted into an exposed portion2105 of transmission layer in a dressing adhered to a patient 200.

FIGS. 5A and 5B illustrate various embodiments of a wound dressing 500which may be trimmable at a bridge portion 530. The dressing 500 maycomprise a backing layer 510, an absorbent layer and/or transmissionlayer formed in a main portion 520 and at least one additional portion540 separated by a gap 560 and connected by a bridge portion 530, and aport 550. In some embodiments, the main portion 520, additional portion540 and bridge portion 530 comprise at least a transmission layer suchas described above between an optional wound contact layer and a backinglayer 510. In any or all of these sections, the dressing 500 may furthercomprise an optional absorbent material such as described positionedbetween the backing layer 510 and the transmission layer. In someembodiments, the absorbent layer may have a similar footprint to thetransmission layer. In other embodiments, the absorbent layer may belocated at main portion 520 and at least one additional portion 540, butthe absorbent layer may not be included in the bridge portion 530. Asillustrated, the dressing has an elongate, rectangular shape, thoughother shapes are also contemplated. The absorbent layer preferably has asmaller footprint than the backing layer, so that the absorbent layer iscompletely surrounded by the backing layer. It will be appreciated thatin some embodiments, the absorbent layer is an integral, one-piece layerof material that extends across the main portion 520, the additionalportion 540 and in the bridge portion 530. Some embodiments may bemanufactured without the port 550 and may include at least one area forattaching a port. For example, the port 550 may simply be an opening inthe backing layer for attaching a separate port member.

The dressing 500 may also comprise other layers as discussed above withrespect to FIGS. 3A-4B. For instance, the dressing 500 may comprise awound contact layer which may be sealed to the backing layer 510,thereby creating an enclosed chamber for the absorbent layer and/ortransmission layer and any other layers within the dressing. The woundcontact layer and backing layer may be sealed along a perimeter with acertain distance from the edge of the sealed perimeter to the edge ofthe absorbent layer. The wound contact layer and backing layer may alsobe sealed together throughout some or all of the area of a gap 560between portions of the inner layers.

The transmission or wicking layer, as described above, may be providedfor the transmission of negative pressure throughout the dressing andfor drawing wound exudate away from the wound site and into the upperlayers of the dressing 500. Some embodiments of the transmission layermay comprise the acquisition distribution layer, as described above withrespect to FIG. 4A, for lateral transmission of fluids such as woundexudate. Some embodiments may employ both a wicking layer and anacquisition distribution layer. Use of one or more of these layers mayadvantageously maintain fluid transmission through narrow portions ofthe dressing such as the bridge portions, and may keep these narrowportions from partially or completely collapsing under negativepressure.

As illustrated in FIG. 5B, the absorbent layer and/or transmission layermay comprise a main portion 520 and a plurality of additional portions540. The additional portions may be smaller than or the same size as themain portion 550. For example, as measured along the longitudinal lengthof a rectangular dressing, the length of the additional portions may besmaller than the length of the main portion, and each additional portionmay have the same length. As illustrated, the main portion 520 isconnected to the first additional portion 540 by one bridge portion 530aligned along the center longitudinal axis of the dressing 500, and eachadditional portion is connected to the next additional portion by asimilar bridge. The bridge portion may in FIGS. 5A and 5B may also belocated off the center axis, for example at the side of the dressing.Other embodiments may employ a plurality of bridges for connecting theportions of the dressing. For example, one embodiment may employ twobridges to connect adjacent portions, wherein the bridges are located atthe side edges of the adjacent portions next to the sealed perimeter.Another embodiment may employ two bridges each located a distance awayfrom the side edges of the adjacent portions.

In some embodiments the main portion 520 may be a precalculated minimumlength, and some or all of the additional portions 540 may have lengthsthat can be removed for custom sizing of the dressing to a variety oflengths exceeding the minimum length. The main portion length may belonger than the additional portion lengths, or the main portion may havethe same length as the additional portions. Such embodiments may beadvantageous for a long incision such as a leg incision made for a veinharvest. In an embodiment, the main portion 520 may be a minimumincision length or minimum leg length, and the additional portions 540may be included in the dressing to achieve a length up to a maximumincision length or a maximum leg length. In use, the dressing may betrimmed according to the incision or leg length of the patient acrossthe bridge portions, for example at cut line 570 described below. Insome embodiments, additional ports or port attachment sites may belocated on some or all of the additional portions in order to maintain asubstantially even level of negative pressure throughout a relativelylong dressing.

The bridge portion 530 in FIGS. 5A and 5B creates a continuous path fornegative pressure delivery between multiple portions of the dressing.The bridge portion 530 may have a width that is less than ⅛, ¼, or ⅓ thewidth of adjacent portions of absorbent material and/or transmissionlayer. A wider bridge portion allows for greater transmission ofnegative pressure and fluids such as wound exudate, however a narrowerbridge portion is advantageous for sealing a dressing trimmed at thebridge portion. Further, patient comfort may be enhanced if the bridgeportion 530 is wide enough to cover a wound or an incision. Embodimentsof the dressings described herein may balance these factors according toa variety of purposes and/or considerations, and therefore the width ofbridge portion 530 may vary. In some embodiments the bridge portion 530may be approximately 15 mm wide, however other embodiments may be 10 mmto 20 mm (or about 10 mm to about 20 mm) wide or thinner or thicker. Inembodiments employing a plurality of bridge portions, the bridgeportions may all be a uniform width or may have varying widths. In someembodiments, the bridge portion 530 may comprise a wound contact layer,a transmission layer (which may be one or both of the wicking layer oracquisition distribution layers described above with respect to FIG.4A), and a backing layer. Some embodiments of the bridge portion 530 mayfurther comprise an absorbent: or superabsorbent layer. The layers inthe bridge portions 530 may be continuous with layers found in theportions 520 or 540 of the dressing, or they may be discrete layerspositioned side-by-side.

In a dressing applied to a nonplanar surface, the bridge portions mayalso advantageously provide enhanced flexing of the dressing forconforming to the nonplanar surface. Further, the bridge portions mayenhance side flexing capabilities of the dressing for covering a curvedor arcuate incision. In some embodiments, the location and width of thebridge portions may be selected for both connecting a plurality oftrimmable portions as well as for flexibility of the dressing.

The dressing 500 may be trimmed at or across the bridge portion 530.Although the dressing may be trimmed at any portion, trimming thedressing at bridge portion 530, for example perpendicular to the lengthof the dressing, enables easier sealing as a narrower cross sectionalarea is exposed, and thus less area requires sealing after trimming. Insome embodiments, the gap 560 may have the same width as the distancefrom the sealed perimeter edge to the absorbent layer, such that whenthe dressing is trimmed along a trim line 570 adjacent to the additionalportion 540 the sealed perimeter around the inner layer(s) issubstantially unchanged. In some embodiments this width may beapproximately 2.5 cm, and in other embodiments may be any width suitablefor maintaining the seal between the backing layer and the wound contactlayer. It will be appreciated that the dressing may be trimmed atlocations other than the illustrated trim line 570, which is includedfor illustrative purposes only, for example at a trim line in the centerof the bridge portion 530 or at a diagonal or curved trim line.

In some embodiments, the absorbent layer and/or other layers of thewound dressing may be prescored for sizing. Other layers, such as thetransmission layer or acquisition distribution layer, may also beprescored. The backing layer may not be scored, as a through hole maylimit the ability of the backing layer to function as a bacterialbarrier or compromise the ability of the dressing to maintain negativepressure. Other embodiments may include a printed or indented pattern onsome or all of the layers to indicate possible trim lines.

After trimming, the dressing 500 may be sealed by an adhesive strip, apiece of a sealing drape, by another dressing, or by a sealant. In someembodiments, a retention strip may be applied at the interface of thedressing edge and the skin. The retention strips may be applied to covertrimmed dressing borders. In some embodiments the retention strips maycomprise a pressure-sensitive adhesive on the lower surface, and inother embodiments may be applied over a sealant. It will be appreciatedthat any other adhesive method or mechanism may be used to seal thedressing. For example, a sealant may be applied with a tool such as asyringe around the trimmed area in order to reseal the chamber of thedressing or to seal the dressing to a patient. Some embodiments of thedressing may be self-sealing.

FIGS. 5C and 5D illustrate removing a portion of dressing from thedressings of FIGS. 5A and 5C thereby exposing a bridging portion oftransmission layer 2105 which can be sealed before or after applying thedressing to a wound site, by means of sealant C dispensed from syringeA. In the case of FIG. 5C, the dressing may simply be suited to aparticular ulcer size, whilst in the case of FIG. 5D, the dressing isadmirably suited to dressing a vein harvest wound running the length ofa subject's leg.

FIG. 6 illustrates an embodiment of a trimmable wound dressing 600comprising a plurality of portions or cells 620. The dressing 600 maycomprise a sealed perimeter 610 of a backing layer and a wound contactlayer, a plurality of cells 620, a plurality of bridges 630 connectingadjacent portions, and a port member 640. As described above, thedressing 600 may be trimmed at the bridge portions and sealed along thetrim line. Each of the cells 620 may include absorbent material and/or atransmission layer as described above, along with other optional layers.The bridge portions 630 may comprise a wound contact layer, atransmission layer (which may be one or both of the wicking layer oracquisition distribution layers described above with respect to FIG.4A), and a backing layer. Some embodiments of the bridge portions 630may further comprise an absorbent or superabsorbent layer. The layers inthe bridge portions 630 may be continuous with layers found in the cells620, or they may be discrete layers positioned side-by-side.

As illustrated, the dressing comprises a 4×4 array of cells 620. Otherembodiments may comprise any suitable array of cells, or may beconfigured as a long rolled dressing N cells wide. The cells may beconnected by one or more narrow bridge portions 630 and separated bygaps 650. The backing layer and wound contact layer may be sealedtogether throughout the gaps. By trimming at the bridge portions 630,the integrity of the dressing may be maintained even as the dressing issignificantly resized. For example, the dressing may be trimmed so thatonly one inner cell or a group of inner cells remain, and the layers ofthe dressing will not separate due to the sealing of the backing layerand wound contact layer throughout the area of the gaps 650.

In some embodiments, the center cells of the dressing 600 may beremoved. This may provide benefits, for example, when the dressing isused to cover a grafted skin flap or sutured skin flap. The dressing maybe resized so that the unsutured skin is substantially uncovered by thedressing. Thus, the removed sections would otherwise cover the healthyskin of the flap. Covering the healthy skin with the dressingpotentially creates problem such as exposing the wound to bacteria onthe surface of the flap and exposing the healthy skin of the flap toexcess moisture. The dressing may also be resized accordingly to covercircular, curved, or otherwise irregularly shaped suture lines.

The port member 640 may be located, as illustrated, on a corner cell ofthe dressing 600. However, in other embodiments the port may be locatedon a different cell. Some embodiments may employ multiple ports, eachport connected to a different cell. For example, a large dressing orlonged rolled dressing may comprise a port at an edge cell of every Nrows, such every as four rows or five rows. Some embodiments may,instead of the illustrated port member 640, comprise a port attachmentsite or sites.

FIG. 6II illustrates removing a portion of dressing from the dressing ofFIG. 6 thereby exposing multiple bridging portions of transmission layerwhich can be sealed before or after applying the dressing to a woundsite, by means of sealant C dispensed from syringe A. It can clearly beseen that the use of bridging portions dramatically reduces thecross-sectional area of transmission layer that must be sealed, reducingthereby both dressing time and risk of leaks.

FIG. 7 illustrates an embodiment of a trimmable wound dressing 700comprising a plurality of portions with multiple port attachment sites760. Similar to the dressing 600 described above, the T-shaped dressing700 comprises a backing layer and wound contact layer having a sealedperimeter 710 around a plurality of cells 720 containing absorbentmaterial and/or a transmission layer connected by bridge portions 730and separated by gaps 740. The bridge portions 730 may comprise a woundcontact layer, a transmission layer (which may be one or both of thewicking layer or acquisition distribution layers described above withrespect to FIG. 4A), and a backing layer. Some embodiments of the bridgeportions 730 may further comprise an absorbent or superabsorbent layer.The layers in the bridge portions 730 may be continuous with layersfound in the cells 720, or they may be discrete layers positionedside-by-side. The backing layer and wound contact layer may also besealed together throughout some or all of the area of the gaps 740. Asdescribed above, the dressing 700 may be trimmed at the bridge portionsand sealed along the trim line. Although the dressing is illustrated asbeing T-shaped, this is for illustrative purposes only, and the dressingmay be a variety of branched shapes. Each branch may comprise one ormore cells connected by one or more bridge portions.

The dressing comprises a plurality of port attachment sites 760. Eachattachment site 760 may be a hole in the backing layer and may becovered with a removable tab 760. The tab may comprise a suitablebacking material with a layer of adhesive on some or all of the lowersurface. Some embodiments may comprise a ring of adhesive sized tosurround the hole 750 in the backing layer. The tab 760 may be removedso that a port may be attached to the backing layer over the hole 750for transmission of negative pressure into the dressing 700. In someembodiments, port attachments may be secured at just one port attachmentsite. In other embodiments, port attachments may be secured over aplurality of attachment sites as needed for transmission of negativepressure throughout the dressing. Some ports may comprise an adhesive onthe lower surface thereof for attachment to the dressing. Someembodiments of the dressing may comprise an adhesive layer for attachingthe port.

FIG. 7II illustrates removing a portion of dressing from the dressing ofFIG. 7 thereby exposing a bridging portion of transmission layer whichcan be sealed before or after applying the dressing to a wound site, bymeans of sealant C dispensed from syringe A. It car clearly be seen thatthis form of trimmable dressing is suitable for difficult to dresswounds which may require some visual inspection and comparison withdressing configurations, for example in the case of a flap wound.

FIG. 8 illustrates an embodiment of a trimmable wound dressing 800 withmultiple port attachment sites 840. The dressing comprises a backinglayer and wound contact layer having a sealed perimeter 710, anabsorbent layer 820, a spacer layer 830 below the absorbent layer, and aplurality of holes 840 in the backing layer covered by tabs 850. Thespacer layer 830 may be one or both of the transmission layer andacquisition distribution layer discussed above. It will be appreciatedthat in some embodiments, only one of the absorbent layer or spacerlayer may be provided, with the other layer being optional.

The dressing 800 is configured as a roll with port attachment sites 840spaced a distance apart along the upper surface. In some embodimentsthis distance may be uniform between all port attachment sites, and inother embodiments the distance may vary. The dressing roll may be customsized by unrolling a length of dressing, trimming the dressing, sealingthe two sides, and attaching a port or ports to one or more portattachment sites. In some embodiments, unused port attachment sites 840may remain sealed by adhesive tabs 850. In some embodiments, the spacerlayer 830, and optionally the absorbent layer 820, may comprise a bridgeportion or plurality of bridge portions located between each portattachment site for ease of sealing a trimmed dressing. It will beappreciated that any of the dressings described above may be configuredas a trimmable roll with a plurality of port attachment sites located adistance apart on the roll. For example, an elongate dressing configuredas a roll may include narrower bridging portions spaced along a lengthof the dressing between port attachment sites to facilitate trimming ofthe dressing to a suitable size.

FIG. 8II illustrates removing a portion of dressing from the dressing ofFIG. 8 thereby exposing multiple bridging portions of transmission layerwhich can be sealed before or after applying the dressing to a woundsite, by means of sealant C dispensed from syringe A.

Such adaptable, resizable dressings may provide the advantage ofreducing the inventory of dressings that a hospital or clinic isrequired to keep. Rather than maintaining a large inventory of dressingsconsisting of a multitude of shapes and sizes for all possible wound orincision sites, a hospital or clinic may only require one or several ofthe dressings described herein which can be modified to suit any patientneeds. Further, it may be advantageous from a manufacturing perspectiveto produce adaptable dressings.

Overview of Example Layer Materials

FIGS. 9A and 9B illustrate one embodiment of spacer layer, ortransmission layer, material which may be used in any of the dressingembodiments described above, and which may also be used in any of theport or fluidic connector embodiments described above. The spacer ortransmission material is preferably formed of a material having a threedimensional structure, and may have a top layer and a bottom layercomprising a knit pattern. For example, a knitted or woven spacer fabric(for example Baltex 7970 weft knitted polyester) or a non-woven fabriccould be used. The top and bottom fabric layers may comprise polyester,such as 84/144 textured polyester or a flat denier polyester. Othermaterials and other linear mass densities of fiber could of course beused. In some embodiments, the top and bottom fabric layers may be thesame pattern and the same material, and in other embodiments they may bedifferent patterns and/or different materials. The top fabric layer mayhave more filaments in a yarn used to form it than the number offilaments making up the yarn used to form the bottom fabric layer, inorder to control moisture flow across the transmission layer.Particularly, by having a filament count greater in the top layer, thatis to say, the top layer is made from a yarn having more filaments thanthe yarn used in the bottom layer, liquid tends to be wicked along thetop layer more than the bottom layer. FIG. 9A illustrates one possibleknit pattern for a top or bottom fabric layer.

As illustrated in the side view of FIG. 9B, between the top and bottomfabric layers may be a plurality of filaments. The filaments maycomprise a monofilament fiber or a multistrand fiber, and may be knittedpolyester viscose or cellulose. In some embodiments, a majority of thefilaments, by volume, may extend vertically (that is, perpendicular tothe plane of the top and bottom layers), or substantially or generallyvertically. In another embodiment, 80%-90% (or approximately 80% toapproximately 90%) of the filaments or more, by volume, may extendvertically, or substantially or generally vertically. In anotherembodiment, all or substantially all of the filaments, by volume, mayextend vertically, or substantially or generally vertically. In someembodiments, a majority, 80%-90% (or approximately 80% to approximately90%) of the filaments or more, or even all or substantially all of thefilaments, extend upward from the bottom fabric layer and/or downwardfrom the top fabric layer, and in some embodiments, such filamentsextend over a length more than half the distance between the top andbottom fabric layers. In some embodiments, a majority, 80%-90% (orapproximately 80% to approximately 90%) of the filaments or more, oreven all or substantially all of the filaments, span a distance that isgreater in a direction perpendicular to the top and bottom fabric layers(a vertical direction) than in a direction parallel to the top andbottom fabric layers (a horizontal direction). The orientation of suchfilaments may promote vertical wicking of fluid through the spacerlayer. In some embodiments, the ratio of the amount of fluid wickedvertically through the spacer material to the amount of fluid wickedlaterally across the spacer material when under negative pressure may be2:1 or more, or approximately 2:1 or more, or may be up to 10:1 or more,or approximately 10:1 or more, in some embodiments. Such filaments mayalso keep the top and bottom layers spaced apart when exposed tocompressive forces or negative pressure. Some embodiments of the spacerlayer may have a tensile strength that substantially prevents tearing bytypical force applied by human hands, and accordingly would need to besevered by other means, such as being cut or sliced, if implemented in atrimmable dressing.

FIGS. 10A-10D illustrate one embodiment of acquisition distributionlayer (ADL) material which may be used in any of the dressingembodiments described above, and which may also be used in any of theport or fluidic connector embodiments described above. To those versedin the art of acquisition distribution layers it would be obvious thatother ADL materials may be used to achieve a similar effect.

FIG. 10A illustrates a backscatter scanning electron microscope (SEM)plan view of a sample portion of acquisition distribution layer materialat 140× magnification. FIG. 10B illustrates an SEM cross sectional viewat 250× magnification. As illustrated in FIG. 10B, a majority of thefiber volume may extend horizontally (that is, parallel to the plane ofthe top and bottom surfaces of the material), or substantially orgenerally horizontally. In another embodiment, 80%-90% (or approximately80% to approximately 90%) or more of the fiber volume may extendhorizontally, or substantially or generally horizontally. In anotherembodiment, all or substantially all of the fiber volume may extendhorizontally, or substantially or generally horizontally. In someembodiments, a majority, 80%-90% (or approximately 80% to approximately90%) of the fibers or more, or even all or substantially all of thefibers, span a distance perpendicular to the thickness of the ADLmaterial (a horizontal or lateral distance) that is greater than thethickness of the ADL material. In some embodiments, the horizontal orlateral distance spanned by such fibers is 2 times (or about 2 times) ormore, 3 times (or about 3 times) or more, 4 times (or about 4 times) ormore, 5 times (or about 5 times) or more, or 10 times (or about 10times) or more the thickness of the ADL material. The orientation ofsuch fibers may promote lateral wicking of fluid through the ADLmaterial. This may more evenly distribute fluid such as wound exudatethroughout the ADL material. In some embodiments, the ratio of theamount of fluid wicked laterally across the ADL material to the amountof fluid wicked vertically through the ADL material under negativepressure may be 2:1 or more, or approximately 2:1 or more, or may be upto 10:1 or more, or approximately 10:1 or more, in some embodiments.

FIG. 10C is a two dimensional microtomographic cross sectional view of acompressed portion of a sample of ADL material which is approximately9.2 mm long. FIG. 10D is an SEM cross sectional view at 130×magnification of the compressed portion illustrated in FIG. 10C. Suchcompressed portions may occur in the ADL material may occur due to theapplication of pressure to the material. FIGS. 10C and 10D furtherillustrate the horizontal network of ADL fibers.

FIGS. 11A and 11B illustrate one embodiment of absorbent material whichmay be used in any of the dressing embodiments described above. FIG. 11Aillustrates a three dimensional microtomographic cross sectional view ofa sample of absorbent material, depicting a fibrous compositioninterspersed with superabsorbent particles. The absorbent material may,for example, be any of the materials described in U.S. Patent Pub. No.2012/308780, titled “Absorbent Structure,” filed May 25, 2012, thecontents of which are hereby incorporated by reference in theirentirety.

FIG. 11B is a cross sectional schematic diagram of an embodiment of theabsorbent material illustrating a plurality of layers within theabsorbent material. The absorbent material may have a textured layer4210 on one side of a fibrous network, the fibrous network defining thebulk of the absorbent material and comprising layers 4220, 4240, and4250. Superabsorbent particles 4230 may be dispersed throughout layers4220, 4240, and 4250. The textured layer 4210, also referred to as the“tissue dispersant layer” in above portions of this specification, maybe configured to laterally transmit fluid. Though depicted as thelowermost layer of the absorbent material, the textured layer 4210 mayin some embodiments be positioned as the uppermost layer of theabsorbent material, and in some embodiments may be positioned as boththe lowermost and uppermost layers of the absorbent material. Thetextured layer 4210 may comprise flat fibers 20 μm to 50 μm in width, orapproximately 20 μm to approximately 50 μm in width. The textured layer4210 may comprise 1 to 2 or approximately 1 to approximately 2 layers ofthe flat fibers, and the textured layer 4210 may have an overallthickness of 0.04 mm, or approximately 0.04 mm.

The bulk of the absorbent material, comprising layers 4220, 4240, and4250, may have a thickness of 1.7 mm, or approximately 1.7 mm, or mayhave a thickness in the range of 0.5 mm to 5.0 mm, or about 0.5 mm toabout 5.0 mm. The bulk of the absorbent material may comprise a mix oftwo fiber types arranged in a fibrous network, for example thecellulosic fiber having a width of 20 μm to 50 μm, or approximately 20μm to approximately 50 μm, and the PE/PET composite fiber, describedabove with respect to the ADL material. The superabsorbent particles4230 may be irregularly shaped and varied in size, and may have adiameter of up to 1 mm, or approximately 1 mm. The superabsorbentparticles 4230 may comprise a sodium acrylate type material. There maybe relatively fewer superabsorbent particles in a portion of theuppermost surface of the bulk of the absorbent material (the surface oflayer 4250 opposite the textured layer 4210), for example in anuppermost surface having a thickness of approximately 0.1 mm.

Layer 4220 may be a liquid absorption layer configured to draw liquidupward through the material towards layers 4240 and 4250. Layer 4240 maybe a storage layer configured to hold absorbed liquid. Layer 4220 may bea liquid distribution layer configured to apply a “reverse suction”effect to the liquid storage layer 4240 in order to inhibit (orsubstantially inhibit) absorbed liquid from leaking back down throughthe lower layers of the absorbent material, a phenomenon which iscommonly known as “back wetting.”

Superabsorbent particles 4230 may be distributed primarily within thestorage layer, may extend partially into the absorption layer 4220 andliquid distribution layer 4250, or may be distributed evenly (orsubstantially evenly) throughout the layers. The layers 4220, 4240, and4250 may overlap with a portion of adjacent layers, and may or may notbe separable.

FIGS. 12A and 12B illustrate one embodiment of obscuring layer materialwhich may be used in any of the dressing embodiments described above.FIG. 12A illustrates a photographic plan view of obscuring material,depicting a material comprising a fibrous network having a reoccurringregularly spaced criss-cross diamond pattern. The diamond shaped patternmay, in one embodiment, be 1.2 mm long by 1.0 mm wide, and may have athickness of approximately 0.04 mm thick, consisting of fibers that aremore densely packed relative to the surrounding area of the material.The diamond shaped pattern may increase structural stability of thefibrous network of the material, for example serving as “tacking”points. FIG. 12B illustrates a three dimensional microtomographicperspective view of the compressed diamond pattern and the surroundinguncompressed fibers.

Some embodiments of the obscuring material may comprise polypropylenespunbond material. Further, some embodiments of the obscuring materialmay comprise a hydrophobic additive or coating, for example ahydrophobic wash designed to permeate the fibers of the obscuringmaterial to make the material substantially waterproof while permittingvapor permeability. Other embodiments may comprise a thin fibrous sheetof 60, 70, or 80 gsm. The fibers of the obscuring material may, in oneembodiment, comprise layers of polypropylene (PP) fibers having a smoothsurface morphology, and the PP fibers may have a thickness ofapproximately 25 μm. In some embodiments, the obscuring material mayhave a thickness of 0.045 mm or about 0.045 mm, or may have a thicknessin the range of 0.02 mm to 0.5 mm, or about 0.02 mm to about 0.5 mm.

FIG. 13 illustrates one embodiment of an adhesive spread onapproximately one square centimeter of a film material, which may beused as the cover or backing layer in any of the dressing embodiments orfluidic connector embodiments described above. The adhesive on the filmhas been covered with carbon powder for ease of illustrating the spreadof the adhesive. The adhesive may comprise, for example, an acrylatetype adhesive, for example K5 adhesive, and may be laid down in a crisscross pattern. In some embodiments, the adhesive material may coverapproximately 45.5%±approximately 1.3% of the film surface. The patternand coverage of the adhesive may vary so long as the configuration issuitable for desired vapor permeability.

I. Overview of Additional Bridged Dressing Embodiments

FIG. 14A (previously FIG. 17A) illustrates a plan view of a trimmabledressing 1600 embodiment wherein the number of layers present in thebridging portions 1620 of the dressing is less than in an absorbent padportion 1630 or a secondary absorbent portion 1650 of the dressing. FIG.14B (previously FIG. 17B) illustrates a side view of the dressing 1600.Accordingly, the overall height of the dressing is reduced at thebridging portions 1620 relative to the absorbent pad portions. In someembodiments, the dressing can also reduce in width at the bridgingportions relative to the absorbent pad portions. The dressing 1600 alsoincludes a port 1640 for delivery of negative pressure.

The dressing 1600 includes a spacer layer 1662 in the absorbent padportion 1630 and secondary absorbent portions 1650. An ADL 1664 extendsacross the length of the dressing through the absorbent pad portion1630, secondary absorbent portions 1650, and bridging portions 1620. TheADL 1664 satisfies the testing criteria specified above and is capableof negative pressure transmission through the bridging portions 1620. Insome implementations of the trimmable dressing 1600, the ADL 1664 may beconstructed from an ADL material that is easier to cut than a spacermaterial, and may be accordingly selected for the bridging portions1620. In other embodiments, the spacer layer 1662 may extend across thelength of the dressing in addition to or instead of the ADL 1664.

In the absorbent pad portion 1630 and secondary absorbent portions 1650,the dressing 1600 includes an absorbent layer 1666 and masking layer1668. In some embodiments, the masking layer 1668 may extend across thebridging portions 1620, and may include holes, windows, perforations, orother visual indicators for indicating to a user where to cut thedressing. For example, perforations may be arranged in a dashed ordotted line configuration along a location within a bridging portion1620, revealing a contrasting color of the ADL 1664 beneath the maskinglayer 1668 to visually indicate a potential location for trimming thedressing 1600. This approach could be extended to include designs andsymbology such as the symbol of a pair of scissors and/or a dotted line,or notches/chevron on each side of the masking layer, letteringindicating a “cut here” location, or the like. The interior layers 1662,1664, 1666, 1668 are positioned between a wound contact layer 1672 and atop film layer 1674 that are sealed together around a perimeter 1610,for example a perimeter of approximately 2.5 cm in some embodiments.

This layer arrangement can provide the advantage of increasedflexibility at the bridging points during wear of the dressing, easycutting with scissors (or other means) during fitting and shaping of thedressing to a wound site, and easier sealing of cut portions. Thereduced height of the bridging portions provides a smaller gap thatneeds to be sealed. Cut or trimmed portions can be sealed with asealant, a sealing strip, a flexible adhesive drape, or other sealingmeans. In addition, use of different top layers in the absorbent padportions compared to the bridging portions can result in a color codeddressing, making the cutting locations clear to the user. Such adressing can be convenient for use along long incision wounds where thelength varies from patient to patient, for example incisions resultingfrom abdominoplasty procedures, as the dressing can be trimmed accordingto specific patient needs.

Referring now to FIG. 15 (formerly FIG. 21), another embodiment of atrimmable dressing 2100 is illustrated. The dressing may comprise, frombottom to top, an optional wound contact layer (not shown), atransmission layer and/or ADL over the wound contact layer, a pluralityof absorbent cells over the transmission layer and/or, and a cover layerover the plurality of absorbent cells. As illustrated in FIG. 15, oneembodiment of the dressing includes a border 2105, a generallyrectangular transmission layer 2110, a number of absorbent cells 2115, aport 2120, and a conduit 2125 for connection of the dressing 2100 to asource of negative pressure. The border 2105 can include a cover layeras described above sealed to the healthy skin of a patient surrounding awound in one example, or can include a cover layer sealed to a woundcontact layer as described above. This cover layer may extend over theplurality of absorbent cells 2115. The port 2120 and conduit 2125 can beconfigured for transmitting negative pressure to the dressing 2100 froma source of negative pressure when in use.

The transmission layer 2110 can extend across the entire central padarea, and can be any material described herein, or the equivalent,having suitable permeability to gas and liquid at a minimum heightand/or width. By having the transmission layer 2110 extend across thecentral pad area rather than only being placed in bridging areas, a morecomfortable distribution of pressure over the patient's therapy site canbe achieved. Such pressure distribution can be considered both from thepoint of view of NPWT delivery and from the point of view of protectingfriable skin, where (depending on the design of the dressing) blisteringcan be caused at pad edges. Therefore, a continuous transmission layercan, in some embodiments, minimize the number of pad edges (i.e. using acontinuous lower layer) providing an advantage for pressuredistribution.

A number of absorbent cells 2115 can be included above the transmissionlayer 2110, and can be any of the absorbent materials described herein,for example with respect to FIGS. 3A-4D and 11A-11B. By cutting thedressing 2100 along the areas of transmission layer 2110 betweenadjacent cells 2115, the dressing 2100 can be adaptively sized tocorrespond to the shape of a patient's wound. The dressing 2100 can besealed along cut portions by one or more of re-sealing of the coverlayer and wound contact layer, through a sealant adhesive, and sealingstrips in various embodiments.

Although the absorbent cells 2115 are illustrated as being triangular inshape, other variations can include circular, oval, square, rectangular,hexagonal, or other shaped cells. Further, although the absorbent cells2115 are illustrated as being discrete portions of absorbent material,in other embodiments the absorbent cells 2115 can be connected bybridging portions.

II. Overview of Additional Layer Materials

FIGS. 16A and 16B (formerly 22A and 22E) illustrate an example ofLibeltex DryWeb T28F that can be suitable for use as acquisitiondistribution layer material (ADL) material which may be used in any ofthe dressing embodiments described above, and which may also be used inany of the port or fluidic connector embodiments described above. Tothose versed in the art of acquisition distribution layers, also knownas “surge layers,” it would be obvious that other ADL materials may beused to achieve a similar effect of laterally wicking fluid. SuitableADL materials can allow for full capacity use. Such ADL layers may becomposed of multiple fiber types and be complex in structure and design.

FIG. 16A illustrates a backscatter scanning electron microscope (SEM)plan view of a sample portion of ADL material at 70× magnification. Asillustrated by FIG. 16A, the ADL material can comprise a number ofnon-woven fibers extending at least partially horizontally (that is,parallel to the plane of the top and bottom surfaces of the material)for laterally/horizontally wicking fluid through the ADL material.

FIG. 16B illustrates an SEM cross sectional view of the ADL material at1550× magnification. In the illustrated embodiment, the ADL material mayconsist of a mix of multiple fiber types. One may be a roughlycylindrical fiber. Another fiber may be a relatively flatter fiberhaving a centrally-located negative space. Another fiber may be amulti-component fiber that has at least one inner core fiber, in someembodiments three inner core fibers as in the illustrated sample, and anouter layer surrounding the inner core.

FIG. 17A (formerly 23A) 17B (23B) and 17C (formerly 23D) illustrate anexample of Libeltex SlimCore TL4 that can be suitable for use asacquisition distribution layer material. FIG. 17A illustrates an SEMcross sectional view of a sample portion of ADL material at 50×magnification. The ADL material can include an upper layer 2305 and alower layer 2310 having different densities, lofts, and thicknesses. Forexample, the upper layer 2305 can comprise a more dense, less loftedfiber configuration and can be approximately 730 μm thick in someembodiments. The lower layer 2310 can comprise a less dense, more loftedfiber configuration and can be approximately 1200 μm thick in someembodiments. FIG. 17B illustrates an SEM plan view of a sample portionof the denser upper layer 2305 at 70× magnification, FIG. 17Cillustrates an SEM plan view of a sample portion of the more loftedlower layer 2310 at 70× magnification. As illustrated by FIGS. 17A-17C,the upper and lower layers 2305, 2310 of the ADL material can comprisedifferent densities of a number of non-woven fibers extending at leastpartially horizontally (that is, parallel to the plane of the top andbottom surfaces of the material) for laterally/horizontally wickingfluid through the ADL material.

As illustrated by FIGS. 17A-17C, the non-woven fibers of the variousillustrated ADL materials can extend more in a horizontal direction thanin a vertical direction to aid in lateral wicking of fluids through thematerial. In some embodiments, a majority of the fiber volume may extendhorizontally or substantially or generally horizontally. In anotherembodiment, 80%-90% (or approximately 80% to approximately 90%) or moreof the fiber volume may extend horizontally, or substantially orgenerally horizontally. In another embodiment, all or substantially allof the fiber volume may extend horizontally, or substantially orgenerally horizontally. In some embodiments, a majority, 80%-90% (orapproximately 80% to approximately 90%) of the fibers or more, or evenall or substantially all of the fibers, span a distance perpendicular tothe thickness of the ADL material (a horizontal or lateral distance)that is greater than the thickness of the ADL material. In someembodiments, the horizontal or lateral distance spanned by such fibersis 2 times (or about 2 times) or more, 3 times (or about 3 times) ormore, 4 times (or about 4 times) or more, 5 times (or about 5 times) ormore, or 10 times (or about 10 times) or more the thickness of the ADLmaterial. The orientation of such fibers may promote lateral wicking offluid through the ADL material. This may more evenly distribute fluidsuch as wound exudate throughout the ADL material. In some embodiments,the ratio of the amount of fluid wicked laterally across the ADLmaterial to the amount of fluid wicked vertically through the ADLmaterial under negative pressure may be 2:1 or more, or approximately2:1 or more, or may be up to 10:1 or more, or approximately 10:1 ormore, in some embodiments.

Features, materials, characteristics, or groups described in conjunctionwith a particular aspect, embodiment, or example are to be understood tobe applicable to any other aspect, embodiment or example describedherein unless incompatible therewith. All of the features disclosed inthis specification (including any accompanying claims, abstract anddrawings), and/or all of the steps of any method or process sodisclosed, may be combined in any combination, except combinations whereat least some of such features and/or steps are mutually exclusive. Theprotection is not restricted to the details of any foregoingembodiments. The protection extends to any novel one, or any novelcombination, of the features disclosed in this specification (includingany accompanying claims, abstract and drawings), or to any novel one, orany novel combination, of the steps of any method or process sodisclosed.

While certain embodiments have been described, these embodiments havebeen presented by way of example only, and are not intended to limit thescope of protection. Indeed, the novel methods and systems describedherein may be embodied in a variety of other forms. Furthermore, variousomissions, substitutions and changes in the form of the methods andsystems described herein may be made. Those skilled in the art willappreciate that in some embodiments, the actual steps taken in theprocesses illustrated and/or disclosed may differ from those shown inthe figures. Depending on the embodiment, certain of the steps describedabove may be removed, others may be added. Furthermore, the features andattributes of the specific embodiments disclosed above may be combinedin different ways to form additional embodiments, all of which fallwithin the scope of the present disclosure.

Although the present disclosure includes certain embodiments, examplesand applications, it will be understood by those skilled in the art thatthe present disclosure extends beyond the specifically disclosedembodiments to other alternative embodiments and/or uses and obviousmodifications and equivalents thereof, including embodiments which donot provide all of the features and advantages set forth herein.Accordingly, the scope of the present disclosure is not intended to belimited by the specific disclosures of preferred embodiments herein, andmay be defined by claims as presented herein or as presented in thefuture.

Throughout the description and claims of this specification, the words“comprise” and “contain” and variations of them mean “including but notlimited to”, and they are not intended to (and do not) exclude othermoieties, additives, components, integers or steps. Throughout thedescription and claims of this specification, the singular encompassesthe plural unless the context otherwise requires. In particular, wherethe indefinite article is used, the specification is to be understood ascontemplating plurality as well as singularity, unless the contextrequires otherwise.

Features, integers, characteristics, compounds, chemical moieties orgroups described in conjunction with a particular aspect, embodiment orexample are to be understood to be applicable to any other aspect,embodiment or example described herein unless incompatible therewith.All of the features disclosed in this specification (including anyaccompanying claims, abstract and drawings), and/or all of the steps ofany method or process so disclosed, may be combined in any combination,except combinations where at least some of such features and/or stepsare mutually exclusive. Details of any foregoing embodiments should notbe considered to be limiting unless expressly indicated as such.Embodiments may relate to any novel one, or any novel combination, ofthe features disclosed in this specification (including any accompanyingclaims, abstract and drawings), or to any novel one, or any novelcombination, of the steps of any method or process so disclosed.

Herein either a full stop or comma is used as the decimal marker.

The reader's attention is directed to all papers and documents which arefiled concurrently with or previous to this specification in connectionwith this application and which are open to public inspection with thisspecification, and the contents of all such papers and documents areincorporated herein by reference.

EXAMPLES

The following Examples are given as non-limiting illustration.

Compositions Commercially available RTV-2 Si compositions having 2 Partsincorporating i), ii) and iii) as defined above, literature values ofphysical properties are publicly available:1 Cavi-Care™ (20 g), Part A and Part B polymers product code 4563 (Smith& Nephew). This is a commercially available open cell foaming in situdressing. Guide cure time within 2 minutes2 Mepiseal™ (3 ml), Part A and Part B polymers ref. 283100 (Mölnlycke)This is a commercially available dispensable adhesive sealant intendedto seal wound exudates within a wound area from contacting intact skin.Guide cure time within 20 minutes3 Elastosil SC870 Part A and B polymers. This is a commerciallyavailable foaming elastomer, black in colour. Guide cure time within 90minutes. (pot life 150 s, tack free time 10-15 min, density 0.35-0.4,Shore hardness 8-12)4 Silpuran® 2445 A/B Part A and B polymers Ref 60063054 and 60063056(both Wacker Chemie AG). This is a commercially available elastomer forcasting as alignment, shock, damping members etc in prosthetics. Guidecure time within 25 minutes5 Silpuran 2400118 A/B (Wacker) is an addition-curing RTV-2 siliconerubber curing to a blue coloured silicone of low hardness. It hasapplication in flexible moulding applications for prosthetics. Guidecure time 120° C. for 1 hour.6 Silpuran 2111 A/B (Wacker) is a commercially available 2-part,addition-curing silicone composition curing to a soft, tacky siliconeadhesive. It is suitable for use in wound dressings. Guide cure time120° C. for 1 hour.7 Elastosil SC835 Part A and B polymers. This is a commerciallyavailable foaming elastomer, reddish brown in colour. Guide cure timewithin 90 minutes (pot life 240 s, tack free time 10-15 min, density0.4-0.45, Shore hardness 20);8 Silbione RTV 4511 A/B (Bluestar)—this commercially availablecomposition is modified to reduce cure time and temperature forapplication at or around a wound site.9 Silbione LSR 4301 A/B (Bluestar)—this commercially available liquidsilicone rubber composition would not be preferred for application at oraround a wound site.

Procedure A

A TNP dressing (PICO™ 15×20 cm) similar (unwaisted) to that illustratedin FIG. 1 was adhered to an acrylic or glass plate or aluminium plate,adhesive side down, and connected to a pump to establish a negativepressure, as illustrated in FIGS. 2B and 2C. Once it was establishedthat a good seal had formed, the pump was turned off and the end portionof the dressing opposite to the pump end was removed by slicing, asshown in FIG. A1. Removing the dressing portion exposed the transmissionlayer and other internal layers as shown in FIGS. 3A-3C.

Sealant composition was loaded into the cylinders of a static mixer anddispensed therefrom to coat the exposed edge of the dressing as in FIG.CII, but with considerable overlap of both the top surface of thedressing adjacent the exposed edge, and the plate. After 90 minutes thepump was turned on again to determine whether a good seal had formed.

Example 1 CaviCare Applied to Dressing Edge

Procedure A followed as above, applying dressing to acrylic plate. Thecomposition was dispensed, and cured within 2 minutes. In thisapplication, the sealed dressing leaked through the open cells of thefoam, although we have observed that the nature of the foam structure ofthis composition causes it to perform differently under differentconditions for example an external load may cause cell collapse withresulting gas impermeability the composition could well be optimised toachieve cell closure. Dispensing was acceptable.

Example 2 Elastosil Applied to Dressing Edge

Procedure A followed as above, applying dressing to acrylic, glass andaluminium plates. Adhesion was better with glass than acrylic and betterwith aluminium than glass. The composition wads dispensed and cured andafter 90 minutes the pump was turned on. Leak was significant for sealedtrimmed dressing on acrylic plate and low level requiring intermittentpump activity, when sealed to glass and aluminium plates. This was afactor of adhesion to the plate, not the dressing to which adhesion wasacceptable. Cured sealant was difficult to remove from acrylic and glasssubstrates, less so from aluminum.

Example 3 Silpuran 2445 Applied to Dressing Edge

Procedure A followed as above, applying dressing to glass plate. Thecomposition was dispensed and left to cure overnight. The sealeddressing performed well, with very good seal established, hardlyrequiring the pump to come on once a negative pressure had beenestablished within the sealed trimmed dressing initially.

Procedure B

Procedure followed as for A above, applying to glass plate, but withinjection of composition directly into exposed transmission (spacer)layer as illustrated in FIGS. EI, BII and CI.

Example 4 CaviCare Injected Directly into Exposed Transmission Layer

Procedure B was followed. The composition did not appear to penetratethe dressing, and seemed to be blocked by the dense superabsorbentpolymer (SAP) layer. On starting the pump, a very poor seal wasobserved, with continual pump activity unable to achieve requiredvacuum.

Example 5 Mepiseal Injected Directly into Exposed Transmission Layer

Result as for Example 4.

Example 6a Elastosil SC 870 Injected Directly into Exposed TransmissionLayer, SAP Removed

Composition was observed to penetrate approx 1 cm within thetransmission layer. On foaming and cure the backing layer top surfacewas observed to lift a little. Good seal, although edge of dressinglifted where composition was present in too great quantity.

Example 6b Silpuran 2445 Injected Directly into Exposed TransmissionLayer, SAP Removed

As Example 6, no dressing lift, good seal and vacuum establishedinstantly.

Example 7 Mepiseal Injected Directly into Exposed Transmission Layer,SAP Removed

As Example 6b, no dressing lift.

Example 8 CaviCare Injected Directly into Exposed transmission Layer,SAP Removed

As Example 6b, but penetration was 1.5-2 cm due to foaming action, nodressing lift. No vacuum due to open cell structure.

CONCLUSION

Gas impermeable curable sealant dispensed externally to cover and/orinternally to impregnate exposed transmission layer was surprisinglyeffective. Seal was absolute, and both modes were visually effective.

Further samples.

Example 9

Procedure a as above was conducted on samples as follows:

9.1 Ostomy Paste

Paste block was worked to render supple and pasted to the dressing edge.Seal was robust. Disadvantages included bioburden risk due to workingbefore application, seal height exceeds dressing height.

9.2 Adhesive Gel Strip

Strip is tacky at both faces, one face applied to dressing gave goodseal; disadvantage of tacky exposed surface, seal degraded over a fewdays as strip lost its tack;

9.3 Shaving Gel

The non-foaming gel was of low viscosity, such that a substantial amountof gel was pulled into the transmission layer, the dressing stoppeddelivering negative pressure, due to the aqueous component of the gelfilling up the superabsorber layer.

9.4 Germolene

The cream was of low viscosity, such that an was pulled into thetransmission layer, the seal collapsed and negative pressure leakageoccurred,

9.5 Savlon Spray

The spray works by forming a liquid film on skin, water evaporates offto leave the polymer medication. In this example, the spray was unableto generate a film which could bridge the interface between absorber andtransmission layer to skin. Two discrete films formed one at the backinglayer surface and one at the wound model representing skin. There was noseal formed.

9.6 Elastosil SC835 (Wacker)

A foam seal of appreciable height was formed at the exposed portion,some composition was drawn in to the transmission layer, to a depth of1-2 mm. The seal adhered strongly to the wound model and seemed robust.

9.7 Elastosil SC870 (Wacker)

A foam seal of appreciable height was formed at the exposed portion,comparable to 9.6. This composition was however more viscous to applyand the resulting seal offers lesser resilience than SC835.

Composition Measurements

Methods were used as described in WO2013076450, the contents of whichare incorporated herein by reference.

Example 10.1 Viscosity Measurement

Viscosity is a measure of the resistance of a fluid to deformation byshear or tensile stress and gives an indication of the fluidity of aliquid, suspension or slurry. The viscosity of a sample is measuredusing a rotational viscometer which simultaneously measures shear rateand shear stress. Vaseline® original, Moisturizing shaving gel Nivea MenOriginals and Germolene, antiseptic cream were independently tested on acone and plate rheometer, using a 2° steel cone of diameter 60 mm. Thesamples were tested across a shear rate range of 5-15 s⁻¹, at 20° C. inaccordance with DIN EN ISO 3219: 1994, Annex B. The viscosity iscalculated using the shear stress at a shear rate of 10 s⁻¹ and is givenin Pa·s.

TABLE viscosity Results Mean Viscosity at shear rate of 10/s, T 23° C.(Pa · s) Cavi-Care Part A 1.643 1.653 1.648 Cavi-Care Part B 1.773 1.8041.7885 Mepiseal part from 42.30 41.97 42.135 chamber with Text Mepisealpart from 34.19 36.10 35.145 chamber without Text Silpuran 2450A 79.4076.32 77.86 Silpuran 2450B 25.20 24.39 24.795 Silpuran 2445A 26.07 20.3923.23 Silpuran 2445B 11.81 12.01 11.91 Silpuran 2400 1.8 Elastosil 835Part A 15 Elastosil 835 Part B 15 Elastosil 870 Part A 50 Elastosil 870Part B 35 Viscosity at shear rate of 10 s⁻¹, T 20° C. (Pa · s)Vaseline ® original, 23.84 pure petroleum jelly, Unilever Moisturisingshaving 11.93 gel, Nivea Men, Originals, Beiersdorf Germolene,antiseptic 14.12 cream (Phenol and Chlorhexidine Digluconate), Bayer plc

Example 10.2 Compressibilty Measurements

Compressibility was determined as a measure of penetration by a plunger.Using a Setamatic Penetrometer with automatic release, timing device andstandard 47.5 g plunger. The instrument was fitted with a hollow plasticcone with a stainless steel tip of mass 15 g. A dwell time of 60 secondswas used.*Measurements were recorded in triplicate (n=3).

Relative mass of parts A B Mean penetration/1/10 mm Silpuran 2400/1850.0% 50.0% 51 (SD 1) A/B* Silpuran 2111 A/B 50.0% 50.0% 200 (SD 3)

Subject to the desired performance requirements of the system thesevalues can be considered acceptable.

Example 10.3 Extensibility, Permanent Set, Tensile Strength, Elongationat Break

Extensibility (kgfcm⁻²) Results Mean Cavi-Care 0.04 0.06 0.04 0.07 0.070.06 Mepiseal 0.07 0.06 0.09 0.07 0.08 0.07 Silpuran 2450 2.60 2.41 2.422.25 2.70 2.48 Silpuran 2445 1.20 1.39 1.32 1.39 1.60 1.38

Permanent Set (%) Results Mean Cavi-Care 0 0 0 0 0 0 Mepiseal 0 0 0 0 00 Silpuran 2450 0 0 0 0 0 0 Silpuran 2445 0 0 0 0 0 0

Tensile Strength (kgfcm⁻²) Results Mean Cavi-Care 0.24 0.27 0.26 0.240.29 0.26 Mepiseal 1.64 0.95 1.77 1.69 2.00 1.61 Silpuran 2450 47.6447.64 55.85 44.37 — 48.87 Silpuran 2445 37.74 39.73 39.98 41.16 37.1539.15 Elastosil 835 450 Elastosil 870 350

Elongation at Break (%) Results Mean Cavi-Care 92 90 83 73 120 92Mepiseal 425 283 463 450 466 418 Silpuran 2450 199 204 234 184 — 205Silpuran 2445 322 332 334 342 302 326 Elastosil SC 870 100 ElastosilSC835 80

Example 11 Extensibility Testing of Spacer Layer (Transmission Layer)Baltex

Reference Description A Spacer Layer B Laminates made with EU33 topfilm, Chemposite 11C-450 Air Laid superabsorber pad, Baltex ref: 7970,batch number T0061Spacer layer and ALLEVYN Gentle Border wound contactlayer (non-sterile and hand manufactured)

Method SOP/QPM/230 (1003423) Extensibility Results

A Test method Results(kgfcm⁻¹) Mean Extensibility (Direction A) 0.070.08 0.08 0.08 1003423 Extensibility (Direction B) 0.07 0.08 0.07 0.071003423

B Test method Results(kgfcm⁻¹) Mean Extensibility (Direction A) 0.580.61 0.59 0.59 1003423 Extensibility (Direction B) 0.79 0.80 0.76 0.781003423

Conclusions

The spacer layer gave good (ie low) extensibility values. Extensibilitywas restricted once the material was incorporated into a dressing withthe superabsorber pad.

Example 12 Silpuran 2400

Silpuran was subject to testing according to procedures A and B above.The results are shown as follows. This composition has a very long curetime and low viscosity and it was expected that it would simply run outof position before curing. In fact the composition demonstrated asurprisingly effective seal, however showed a dramatic performancedifference depending on dispensing according to presence or absence ofthe absorber layer in Procedure B. The composition gave excellentresults when dispensed according to Procedure B.

Silpuran 2400 was then dispensed internally according to the firstembodiment procedure illustrated in FIG. C1. The composition wasretained admirably in the transmission layer, and only a small volume ofcomposition was required. This enables use of a small volume syringewith associated back-pressure advantages. It was important to use asmall bore nozzle to minimize run off, allowing as little composition aspossible to contact skin. Dispensing again was ineffective using theProcedure A method with superabsorber layer, but was highly effectivefor Procedure B with single transmission layer in the trimmed portion.The transmission layer may be spacer or ADL, but with a preference foromitting obscuring layer to monitor the dispensing and seal formation,the transmission layer is preferably an ADL-type layer or a combinationof ADL and spacer, minimizing the risk of spacer layer puncturing thebacking layer.

Composition: Silpuran 2400/20, Part A and Part B polymers (Wacker)

Silpuran 2400 Component A

Color translucent

Viscosity (Plate/Cone) DIN EN ISO 3219 1800 mPa s

Density DIN EN ISO 2811 1.00 g/cm³

Component B

Color translucent

Viscosity (Plate/Cone) DIN EN ISO 3219 1800 mPa s

Density DIN EN ISO 2811 1.00 g/cm³Product data (catalyzed A+B)Mix ratio A:B1:1Color translucentPot life at 23° C. 21 minProduct data (cured)

Hardness Shore A ISO 868 7 Hardness Shore 00 ASTM 2240/Type 00 55

Tensile strength ISO 37 2.00 N/mm2Elongation at break ISO 37 600%Tear strength ASTM D 624 B 3.0 N/mmCuring conditions: 10 min/100° C.

Run 8A

Followed as detailed in procedure A of the patent spec with applicationof Silpuran 2400/20.Dressing before application of Silpuran 2400/20Dressing immediately after application of Silpuran 2400/20A torch/flash used to examine the reflection of the silicone and ensureno pin holes were present in the composition immediately followingapplication.Cured composition (90 minutes was allowed to elapse, and cure beyondmanual kinetic point confirmed). Sealant was not effective as there wasno cured sealant across the cut face. Gap demonstrated

Run 8B

Followed as detailed in procedure B of the patent spec with applicationof Silpuran 2400/20.Dressing before application of Silpuran 2400/20Dressing immediately after application of Silpuran 2400/20Cured composition (90 minutes was allowed to elapse, and cure beyondmanual kinetic point confirmed) Sealant was effective when it had beendispensed into the transmission layer directly.

It was noted that whilst the spacer layer was more resilient tocompression when the cured silicone was inside it then the unfilledspacer; by comparison to run 8A where the same sealant had been appliedacross the cut face the profile of the sealant was less pronounced and(subjectively) the rigidity was significantly less.

The following observations were made:

Significantly less sealant was needed when sealing the internal space ofthe transmission layer as opposed to sealing over the cut end.

The resulting finish was significantly neater when the sealant wasapplied into the internal space of the transmission layer as opposed tosealing over the cut end. The silicone that flowed onto the wound modelcame from the fact that the nozzle aperture was not sufficient topenetrate the spacer layer deeply and was thus delivering silicone closeto the edge of the cut transmission layer. A dispensing nozzle withexternal bore small enough to penetrate the transmission layer could beinserted into the transmission layer (to a selected distance) at thetime of dispensing and limit the amount of curing silicone that was ableto travel the distance back out of the transmission layer.

The absence of an obscuring layer or opaque layer above the bridge inRun 8B (such as the absorbent layer present in Run 8A) allowed the userto clearly see the ingress of the sealant into the bridge duringdispensing. This provided control over where to apply the sealant, howmuch and allowed the user to ensure that no air paths remained in theseal.

The low viscosity of Silpuran 2400/20 was a significant advantage duringdispensing. It flowed well into the transmission layer and appeared toreadily conform to the internal shape of the transmission layer. A lowviscosity material would also have the added advantage of reducing theback pressure generated in a dispensing unit. This could be ofparticular importance if a dispensing nozzle with narrow aperture wasused (as desired to penetrate the transmission layer) so that the backpressure generated by the liquid travelling through the resultant narroworifice was reduced. To provide an example of the influence of backpressure, in a dispenser comprising a double barrelled syringe withintegral mixer it would relate to the force that the user needed toapply to the syringe plunger to eject the liquid.

Example 13 Dispenser Design

A dispenser with a single nozzle that penetrated the transmission layercould be an advantage.

A dispenser with multiple nozzles could be an advantage, however,subject to the width of this head, injecting the sealant into a dressingfollowing body contours be limited. Therefore either the width of themixing head should be balanced so as to ensure ease of application(wider better) versus following body contours (narrower better).

Or the mixing heads should be conformable so as to be moved to shape(ideally this would stay in position once moved) to allow the user toapproximate the shape.

Thought should be given to the clearance of the dispenser given that itwill be entering the transmission at an acute angle to the skin.

Results of Foregoing Examples are Illustrated as Follows:

Example 6b resultsExp 3 Silpuran 2445

1. A system for treatment of a wound site, the system comprising: adispensable composition for wound care; and a wound dressing comprising:a backing layer having an upper surface and a lower surface and defininga perimeter configured to be positioned over skin surrounding the woundsite; one or more transmission layers configured to be positioned belowthe backing layer; and a port configured to transmit negative pressurethrough the backing layer for the application of topical negativepressure at the wound site; wherein the wound dressing is configured forremoval of a portion of the wound dressing directly enclosing thetransmission layer to create a main wound dressing portion with one ormore exposed portions wherein the transmission layer is exposed at aportion thereof, wherein the dispensable composition is configured toform a seal at a location of the one or more exposed portions. 2-12.(canceled)
 13. The system of claim 1, wherein the dispensablecomposition comprises a silicone curing system including one, two ormore parts silicone.
 14. (canceled)
 15. The system of claim 1, whereinthe dispensable composition comprises an RTV-2 silicone curing system.16. The system of claim 1, wherein the dispensable compositioncomprises, apportioned between at least one Part A and at least one PartB: one or more alkenyl-group containing polymers (i) having at least onealkenyl group or moiety per molecule, one or more SiH-containingpolymers (ii) having at least one Si—H unit per molecule; a catalyst(iii) for curing by addition of alkenyl-containing polymer (i) toSiH-containing polymer (ii); wherein the dispensable composition curesto an elastomer which is fluid-impermeable at an exposed surfacethereof.
 17. The system of claim 1, further comprising, for dispensingthe dispensable composition, a syringe or static mixer having a nozzlehead comprising a spreader tip with plural nozzles.
 18. (canceled) 19.The system of claim 1, wherein the dispensable composition is selectedfrom compounds including siloxanes, modified siloxanes, polyester,polyether urethanes, elastomeric polyether polyesters, polyglycolicacid, ethyl vinyl acetate, polyacrylate, polyacid derivatives ofpolysaccharides, carboxyalkylcellulose, carboxyalkylchitosan andcopolymers thereof, and hybrids of the compounds, the hybrids includingcopolymers, entangled systems and mixtures thereof.
 20. (canceled) 21.The system of claim 1, further comprising cooperative dispensing devicecomprising at least one sealed barrel or at least one cassette for astatic mixer. 22-34. (canceled)
 35. A method of treating a wound,comprising: providing a wound dressing comprising: a backing layer; andone or more transmission layers positioned beneath the backing layer;removing a portion of the wound dressing to create a main wound dressingportion with one or more exposed portions, wherein the one or moretransmission layers is exposed at the one or more exposed portions;positioning the main wound dressing portion over a wound; sealing themain wound dressing portion to skin surrounding the wound; anddispensing a composition to a location at or within the one or moreexposed portions of the main wound dressing portion thereby sealing theone or more exposed portions.
 36. (canceled)
 37. (canceled)
 38. Themethod of claim 35, wherein dispensing the composition comprisesinternally impregnating the one or more transmission layers at the oneor more exposed portions.
 39. (canceled)
 40. (canceled)
 41. The methodof claim 38, further comprising impregnating the one or moretransmission layers to a distance in the range of 0.2 to 25 mm withinthe one or more transmission layers.
 42. The method of claim 35, furthercomprising applying negative pressure to the wound through the backinglayer of the main wound dressing portion.
 43. The method of claim 42,further comprising drawing the dispensable composition up to 25 mmwithin the one or more transmission layers at the one or more exposedportions via the negative pressure.
 44. The method of claim 42, whereinthe wound dressing exhibits no change or substantially no change incompressibility at the location of the seal on initiation of thenegative pressure.
 45. The method of claim 42, further comprisingdispensing the dispensable composition with formation of an air-tightelastomer which is capable of containing the negative pressure.
 46. Themethod of claim 35, wherein the dispensable composition has a viscosityin the range of 11 and 14 Pa·s.
 47. The method of claim 35, wherein thedispensable composition, when cured, is conformable.
 48. The method ofclaim 35, further comprising subjecting the dispensable composition toshear forces during application to the one or more exposed portions,wherein the dispensable composition reduces viscosity when subjected tothe shear forces.
 49. The method of claim 35, wherein the dispensablecomposition has a curing time at 23° C. in the range from 0.5 to 5 min.50. The method of claim 35, wherein the dispensable composition has acuring time at 32° C. in the range from 0.5 to 7 min.
 51. The method ofclaim 35, further comprising dispensing the dispensable compositiondirectly at the exposed portion through an exposed face of the one ormore transmission layers.